bluuebunny/crossref_metadata_2025 huggingface dataset:
Thrombin Inhibits NMDA‐Mediated Nociceptive activity in the Mouse: Possible Mediation by Endothelin
Authors: Fang Ming , Kovács Katalin J. , Fisher Lauralei L. , Larson Alice A.
Published: April 2003

The CNS expresses many components of an extracellular protease signalling system, including the protease‐activated receptor‐1 (PAR‐1) whose tethered ligand is generated by thrombin. Activation of PAR‐1 potentiates NMDA receptor activity in hippocampal neurons. Because NMDA activity mediates hyperalgesia, we tested the hypothesis that PAR‐1 receptors also regulate pain processing. In contrast to the potentiating effect of thrombin in the hippocampus, NMDA‐induced behaviours and the transient mechanical hyperalgesia (von Frey fibres) induced by intrathecally injected NMDA in mice were inhibited by thrombin in a dose‐related fashion. This anti‐hyperalgesic effect was mimicked by SFLLRN, the natural ligand at PAR‐1 binding sites, but not SLIGRL‐amide, a PAR‐2 agonist. The effects of SFLLRN were less potent and shorter in duration than that of thrombin, consistent with its more transient effect on PAR‐1 sites. Both thrombin and SFLLRN inhibited acetic acid‐induced abdominal stretch (writhing) behaviours, which were also sensitive to NMDA antagonism, but not hot plate or tail flick latencies, which were insensitive to NMDA antagonists. TFLLR‐amide, a selective ligand for PAR‐1 sites, mimicked the effects of thrombin while RLLFT‐amide, an inactive, reverse peptide sequence, did not. In addition, the effect of TFLLR‐amide was prevented by RWJ‐56110, a PAR‐1 antagonist. Thrombin and TFLLR‐amide produced no oedema (Evans Blue extravasation) in the spinal cord that would account for these effects. Based on the reported ability of thrombin to mobilize endothelin‐1 from astrocytes, we tested the role of this compound in thrombin's activity. BQ123, an endothelin A receptor antagonist, prevented thrombin's inhibition of writhing and NMDA‐induced behaviours while BQ788, an endothelin B receptor antagonist, did not. Thus, activation of PAR‐1 sites by thrombin in the CNS appears to inhibit NMDA‐mediated nociception by a pathway involving endothelin type A receptors.
In Vivo and In Vitro Heterogeneity of Segment Length Changes in the Semimembranosus Muscle of the Toad
Authors: Ahn A. N. , Monti R. J. , Biewener A. A.
Published: April 2003

Many studies examine sarcomere dynamics in single fibres or length–tension dynamics in whole muscles in vivo or in vitro, but few studies link the various levels of organisation. To relate data addressing in vitro muscle segment behaviour with in vivo whole muscle behaviour during locomotion, we measured in vivo strain patterns of muscle segments using three sonomicrometry crystals implanted along a fascicle of the semimembranosus muscle in the American toad (Bufo americanus; n= 6) during hopping. The centre crystal emitted an ultrasonic signal, while the outer crystals received the signal allowing the instantaneous measurement of lengths from two adjacent muscle segments. On the first day, we recorded from the central and distal segments. On the second day of recordings, the most distal crystal was moved to a proximal position to record from a proximal segment and the same central segment. When the toads hopped a distance of two body lengths, the proximal and central segments strained −15.1 ± 6.1 and −14.0 ± 4.9 % (i.e. shortening), respectively. Strain of the distal segment, however, was significantly lower and more variable in pattern, often lengthening before shortening during a hop. From rest length, the distal segment initially lengthened by 2.6 ± 2.0 % before shortening by 6.5 ± 3.2 % at the same hop distance. Under in vitro conditions, the central segment always shortened more than the distal segment, except when passively cycled, during which the segments strained similarly. When the whole muscle was cycled sinusoidally and stimulated phasically in vitro, the two adjacent segments strained in opposite directions over much (up to 34 %) of the cycle. These differences in strain amplitude and direction imply that two adjacent segments can not only produce and/or absorb varying amounts of mechanical energy, but can also operate on different regions of their force–length and force–velocity relationships when activated by the same neural signal. Understanding regional differences in contractile dynamics within muscles is therefore important to linking our understanding of sarcomere behaviour with whole muscle behaviour during locomotion.
Antibodies to Periodontal Pathogens Are Associated With Coronary Heart Disease
Authors: Pussinen Pirkko J. , Jousilahti Pekka , Alfthan Georg , Palosuo Timo , Asikainen Sirkka , Salomaa Veikko
Published: April 2003

Objective—

We analyzed the association of coronary heart disease (CHD) and serology of periodontitis in a random sample (n=1163) of men (aged 45 to 74 years) by determining serum IgG-antibodies to
Actinobacillus actinomycetemcomitans
and
Porphyromonas gingivalis
.

Methods and Results—

CHD (n=159) was more prevalent among edentulous than dentate subjects (19.8% and 12.1%,
P
=0.003). In the dentate population, CHD was more common among subjects seropositive for
P. gingivalis
compared with those seronegative (14.0% and 9.7%,
P
=0.029). Accordingly, CHD was more prevalent in subjects with a high combined antibody response than those with a low response (17.4% and 11.1%,
P
=0.026). When adjusted for age and several CHD risk factors, the subjects with a high combined antibody response had an odds ratio of 1.5 (95% CI, 0.95 to 2.50,
P
=0.077) for prevalent CHD. In a linear regression model, the combined antibody response was directly associated with prevalent CHD (
P
=0.046) and inversely with serum HDL cholesterol concentration (
P
=0.050).

Conclusions—

In conclusion, edentulousness and serum antibodies to major periodontal pathogens were associated with CHD. This suggests that periodontal infection or response of the host against the infection may play a role in the pathogenesis of CHD.
Impact of Weight Loss on Inflammatory Proteins and Their Association With the Insulin Resistance Syndrome in Morbidly Obese Patients
Authors: Kopp H.P. , Kopp C.W. , Festa A. , Krzyzanowska K. , Kriwanek S. , Minar E. , Roka R. , Schernthaner G.
Published: April 2003

Objective—

Obesity is closely linked to the insulin resistance syndrome (IRS), type 2 diabetes, and cardiovascular disease, the primary cause of morbidity and mortality in these patients. Elevated levels of C-reactive protein (CRP) and interleukin-6 (IL-6), indicating chronic subclinical inflammation, have been associated with features of the IRS and incident cardiovascular disease.

Methods and Results—

We studied the cross-sectional and longitudinal relation of CRP, IL-6, and tumor necrosis factor-α (TNF-α) with features of the IRS in 37 morbidly obese patients with different stages of glucose tolerance before and 14 months after gastric surgery. Weight loss after gastric surgery induced a significant shift from diabetes (37% vs 3%) to impaired glucose tolerance (40% vs 33%) and normal glucose tolerance (23% vs 64%). The baseline concentration of IL-6 was correlated with TNF-α (
r
=0.59,
P
<0.01) and CRP (
r
=0.44,
P
<0.05) levels. TNF-α, IL-6, and CRP were significantly correlated with insulin resistance estimated by the homeostatic model assessment (
r
=0.48,
P
<0.05;
r
=0.56,
P
<0.01; and
r
=0.35,
P
<0.05, respectively). Concentrations of CRP and IL-6 decreased after weight loss (median, 8.6 and interquartile range, 2.7/14.5 vs 2.5 and 1.2/4.1 mg/L;
P
<0.006, and 5.13 and 2.72/12.15 vs 3.95 and 1.97/5.64 pg/mL,
P
<0.02, respectively), whereas serum levels of TNF-α remained unchanged (8.6 and 6.3/18.8 vs 11.7 and 5.8/17.2 pg/mL; NS.). Multiple regression analysis revealed that the decrease in insulin resistance remained independently and significantly correlated with the decrease in IL-6 concentrations (
P
<0.01) and the decrease in body mass index with the decrease in CRP (
P
<0.05), respectively.

Conclusions—

Weight loss in morbidly obese patients induces a significant decrease of CRP and IL-6 concentrations in association with an improvement of the IRS.
Rapid Activation of Ras by Fluid Flow Is Mediated by Gα
q
and Gβγ Subunits of Heterotrimeric G Proteins in Human Endothelial Cells
Authors: Gudi Sivaramaprasad , Huvar Ivana , White Charles R. , McKnight Nathan L. , Dusserre Nathalie , Boss Gerry R. , Frangos John A.
Published: April 2003

Objective—

Temporal gradients in fluid shear stress have been shown to induce a proatherogenic phenotype in endothelial cells. The biomechanical mechanism(s) that enables the endothelium to respond to fluid shear stress requires rapid activation and signal transduction. The small G protein Ras has been identified as an early link between rapid mechanotransduction events and the effects of shear stress on downstream signal-transduction cascades. The aim of this study was to elucidate the upstream mechanotransduction signaling events mediating the rapid activation of Ras by fluid shear stress in human endothelial cells.

Methods and Results—

Direct measurement of Ras-bound GTP and GDP showed that fluid-flow activation of Ras was rapid (10-fold within 5 seconds) and dose dependent on shear stress magnitude. Treatment with protein tyrosine kinase inhibitors or pertussis toxin did not significantly affect flow-induced Ras activation. However, activation was inhibited by transient transfection with antisense to Gα
q
or the Gβγ scavenger β-adrenergic receptor kinase carboxy terminus. Transfection with several Gβγ subunit isoforms revealed flow-induced Ras activation was most effectively enhanced by Gβ
1γ2
.

Conclusions—

These results suggest that the rapid, shear-induced activation of Ras is mediated by Gα
q
through the activity of Gβγ subunits in human vascular endothelial cells.
Third-Generation β-Blockers Stimulate Nitric Oxide Release From Endothelial Cells Through ATP Efflux
Authors: Kalinowski Leszek , Dobrucki Lawrence W. , Szczepanska-Konkel Miroslawa , Jankowski Maciej , Martyniec Ludmila , Angielski Stefan , Malinski Tadeusz
Published: May 2003

Background—

Nebivolol and carvedilol are third-generation β-adrenoreceptor antagonists, which unlike classic β-blockers, have additional endothelium-dependent vasodilating properties specifically related to microcirculation by a molecular mechanism that still remains unclear. We hypothesized that nebivolol and carvedilol stimulate NO release from microvascular endothelial cells by extracellular ATP, which is a well-established potent autocrine and paracrine signaling factor modulating a variety of cellular functions through the activation of P2-purinoceptors.

Methods and Results—

Contraction and relaxation of renal glomerular vasculature were measured by determination of intracapillary volume with [
3
H]-inulin. Biologically active NO was measured with highly sensitive porphyrinic NO microsensors in a single glomerular endothelial cell (GEC). Extracellular ATP was measured by a luciferin-luciferase assay. Enzymatic degradation of extracellular ATP by apyrase and blockade of P2Y-purinoceptors by suramin or reactive blue 2 inhibited both β-blocker–induced glomerular vasorelaxations and β-blocker–stimulated NO release from GECs. Both β-blocker–induced vasorelaxations were in the micromolar concentration range identical to that required for the β-blocker stimulation of ATP and NO release from GECs. The maximum of NO release for nebivolol and carvedilol was very similar (188±14 and 226±17, respectively). Blockade of ATP release by a mechanosensitive ion channel blocker, Gd
3+
, inhibited the β-blocker–dependent release of ATP and NO from GECs.

Conclusions—

These results demonstrate for the first time that nebivolol and carvedilol induce relaxation of renal glomerular microvasculature through ATP efflux with consequent stimulation of P2Y-purinoceptor–mediated NO release from GECs.
Effects of Continuous Enhanced Vagal Tone on Dual Atrioventricular Node and Accessory Pathways
Authors: Chiou Chuen-Wang , Chen Shih-Ann , Kung Ming-Ho , Chang Mau-Song , Prystowsky Eric N.
Published: May 2003

Background—

The aim of this study was to test the electrophysiological effects of continuous enhanced vagal tone on dual atrioventricular (AV) nodal and accessory pathways.

Methods and Results—

This study included 10 patients with typical, slow-fast AV nodal reentrant tachycardia (AVNRT) and 10 patients with AV reciprocating tachycardia. Electrophysiological data were measured before and during continuous vagal enhancement by using phenylephrine infusion (0.6 to 1.5 μg/kg per min). For patients with AVNRT, during phenylephrine infusion, 1:1 conduction times over the anterograde fast and slow and retrograde fast pathways were prolonged (453±64 to 662±120 ms,
P
<0.001; 379±53 to 443±95 ms,
P
<0.05; 405±112 to 442±118 ms,
P
<0.05). The effective refractory period and functional refractory period of the anterograde fast pathway were prolonged with phenylephrine (394±73 to 544±128 ms,
P
<0.001; 454±60 to 596±118 ms,
P
<0.001). In contrast, the effective refractory period and functional refractory period of the anterograde slow and retrograde fast were not significantly changed. No significant change was observed in the conduction or refractoriness of the accessory pathways in patients with AV reciprocating tachycardia nor in atrial or ventricular refractoriness.

Conclusions—

Enhanced vagal tone produces disparate effects on the refractoriness of the slow and fast AV nodal conduction pathways, with the anterograde fast pathway being the most sensitive. These changes are conducive to induction of AVNRT with a premature atrial complex and may explain in part the relatively common occurrence of AVNRT during sleep or other periods of presumed increased parasympathetic tone.
An Underrecognized Subepicardial Reentrant Ventricular Tachycardia Attributable to Left Ventricular Aneurysm in Patients With Normal Coronary Arteriograms
Authors: Ouyang Feifan , Antz Matthias , Deger Florian T. , Bänsch Dietmar , Schaumann Anselm , Ernst Sabine , Kuck Karl-Heinz
Published: May 2003

Background—

In patients with apparently normal hearts, ventricular tachycardia (VT) may only involve the subepicardial myocardium.

Methods and Results—

Four patients with exercise-induced fast VT with right bundle branch block morphology were investigated. ECG showed a small q wave in leads II, III, and aVF during sinus rhythm (SR) in all 4 patients. Left ventricular angiography showed small inferolateral aneurysms in all patients. Coronary arteriograms were normal in all 4 patients. Six unstable VTs (cycle length, 200 to 305 ms) and 1 stable VT (cycle length 370 ms) were reproducibly induced in the 4 patients. During SR, endocardial mapping was normal in all 4 patients, and epicardial mapping showed fragmented and late potentials in the left inferolateral wall anatomically consistent with the left ventricle aneurysm. During tachycardia, epicardial mapping showed a macroreentrant VT with focal endocardial activation in the patient with stable VT, whereas in 2 patients with unstable VT, a diastolic potential was only recorded and coincided with the late potential in the same area. Epicardial ablation was performed in 3 patients and successfully abolished those VTs. No VT recurred in 2 patients during follow-up of 2 and 9 months. Clinical VT recurred 6 months after the ablation and was successfully ablated in a repeated epicardial ablation in 1 patient. In the remaining patient without epicardial ablation, an implantable cardiac defibrillator was implanted. There were multiple shocks during a follow-up of 31 months.

Conclusions—

In patients with normal coronary arteriograms and left ventricle aneurysm, exercise-induced VT with right bundle branch block morphology may have a subepicardial arrhythmogenic substrate, which may be amenable to epicardial ablation.
Differentiation of Human Embryonic Stem Cells to Cardiomyocytes
Authors: Mummery Christine , Ward-van Oostwaard Dorien , Doevendans Pieter , Spijker Rene , van den Brink Stieneke , Hassink Rutger , van der Heyden Marcel , Opthof Tobias , Pera Martin , de la Riviere Aart Brutel , Passier Robert , Tertoolen Leon
Published: May 2003

Background—

Cardiomyocytes derived from human embryonic stem (hES) cells could be useful in restoring heart function after myocardial infarction or in heart failure. Here, we induced cardiomyocyte differentiation of hES cells by a novel method and compared their electrophysiological properties and coupling with those of primary human fetal cardiomyocytes.

Methods and Results—

hES cells were cocultured with visceral-endoderm (VE)–like cells from the mouse. This initiated differentiation to beating muscle. Sarcomeric marker proteins, chronotropic responses, and ion channel expression and function were typical of cardiomyocytes. Electrophysiology demonstrated that most cells resembled human fetal ventricular cells. Real-time intracellular calcium measurements, Lucifer yellow injection, and connexin 43 expression demonstrated that fetal and hES-derived cardiomyocytes are coupled by gap junctions in culture. Inhibition of electrical responses by verapamil demonstrated the presence of functional α
1c
-calcium ion channels.

Conclusions—

This is the first demonstration of induction of cardiomyocyte differentiation in hES cells that do not undergo spontaneous cardiogenesis. It provides a model for the study of human cardiomyocytes in culture and could be a step forward in the development of cardiomyocyte transplantation therapies.
Inhibitory Activity of Clinical Thiazolidinedione Peroxisome Proliferator Activating Receptor-γ Ligands Toward Internal Mammary Artery, Radial Artery, and Saphenous Vein Smooth Muscle Cell Proliferation
Authors: de Dios Stephanie T. , Bruemmer Dennis , Dilley Rodney J. , Ivey Melanie E. , Jennings Garry L.R. , Law Ronald E. , Little Peter J.
Published: May 2003

Background—

The proliferation of vascular smooth muscle cells (VSMCs) is a known response to arterial injury that is an important part of the process of restenosis and atherosclerosis. People with diabetes have an increased risk of cardiovascular disease resulting from accelerated coronary atherosclerosis. The newest drugs for Type 2 diabetes are thiazolidinediones, which are insulin-sensitizing peroxisome proliferator activating receptor-γ (PPARγ) ligands. We investigated the antiproliferative effects of troglitazone, rosiglitazone, and pioglitazone on VSMCs derived from the three vascular beds used for coronary artery by-pass grafting: the internal mammary and radial artery and saphenous veins.

Methods and Results—

The three vessels yielded proliferating cells of slightly differing morphology. Inhibition of cell proliferation was assessed by cell counting and cell cycle studies by Western blotting for phosphorylated retinoblastoma protein. All three thiazolidinediones showed inhibitory potency toward cell proliferation with a potency troglitazone>rosiglitazone≈pioglitazone, and this potency profile was maintained toward the growth factor and insulin-stimulated phosphorylation of the retinoblastoma protein, which controls cell cycle progression.

Conclusion—

The inhibitory potency of clinical thiazolidinediones toward different vascular sources is dependent on the individual thiazolidinedione and very little on the vascular source.
Intramural Delivery of Recombinant Apolipoprotein A-I
Milano
/Phospholipid Complex (ETC-216) Inhibits In-Stent Stenosis in Porcine Coronary Arteries
Authors: Kaul Sanjay , Rukshin Vladimir , Santos Raul , Azarbal Babak , Bisgaier Charles L. , Johansson Jan , Tsang Vivian T. , Chyu Kuang-Yuh , Cercek Bojan , Mirocha James , Shah Prediman K.
Published: May 2003

Background—

We have previously demonstrated vasculoprotective effects after repeated intravenous administration of recombinant apolipoprotein A-I
Milano
(apoA-I
m
)/phospholipid complex. In this study, we sought to determine the effects of local recombinant apoA-I
m
/1-palmitoyl,2-oleoyl phosphatidylcholine complex (ETC-216) delivered intramurally via the Infiltrator catheter on luminal narrowing in a porcine coronary artery stent overstretch injury model.

Methods and Results—

In twelve domestic swine (≈25 kg), two arteries each were infiltrated with 0.4 mL ETC-216 (14 mg/mL) or vehicle control immediately before deployment of GFX stents (stent:artery ratio=1.3:1). Animals were euthanized at day 28, and evaluation by QCA revealed a significant improvement in mean lumen loss index with ETC-216 treatment (21±22% versus 43±13% lumen loss;
P
=0.01). Histomorphometric analysis showed that ETC-216 treatment significantly reduced the intimal area (6.7±1.5 versus 5.2±1.4 mm
2
, −22%;
P
=0.02) and the stenosis index (0.76±0.15 versus 0.59±0.15;
P
=0.01), and increased the lumen area (2.1±1.4 versus 3.7±1.8 mm
2
, +76%;
P
=0.02). Regression analysis showed significant differences in lumen area (
P
=0.004), neointimal area (
P
=0.003), stenosis index (
P
=0.001), and neointimal thickness (
P
=0.003) adjusted for injury score in favor of ETC-216.

Conclusions—

A single intramural administration of ETC-216 significantly inhibited injury-induced luminal narrowing in the porcine stent overstretch model through reduction of intimal hyperplasia. These data show that local intracoronary delivery of ETC-216 may be useful to prevent restenosis after coronary stenting.
Functional Role of ET
B
Receptors in the Renal Medulla
Authors: Vassileva Ivanka , Mountain Christy , Pollock David M.
Published: April 2003

Experiments were conducted to determine the influence of ET
B
receptors in the control of renal medullary function. The acute relation between renal perfusion pressure (RPP) and natriuresis was examined in anesthetized rats treated with the ET
B
antagonist A-192621 (10 mg/kg IV). In A-192621–treated rats, sodium excretion (UNaV) was 0.4±0.1, 0.6±0.3, and 2.7±0.5 μmol/min at RPP of 80±1, 107±1, and 144±5 mm Hg, respectively. In control rats, UNaV averaged 0.8±0.4, 3.4±1.2, and 8.1±1.7 μmol/min at RPP of 77±2, 115±5, and 137±3 mm Hg, respectively. For normal and high RPP, UNaV was significantly lower in A-192621–treated rats compared with control rats. Additional experiments determined the effects of Big ET-1 (10 pmol/kg per minute) on intrarenal blood flow. Medullary blood flow (MBF) and cortical blood flow were measured in anesthetized rats by single-fiber, laser Doppler flowmetry. Cortical blood flow significantly decreased in response to Big ET-1 in rats on a normal or high salt diet. Big ET-1 significantly increased MBF in rats on a high salt diet, whereas there was no change in MBF in rats on a normal salt diet. These results demonstrate that medullary vasodilation produced by Big ET-1 is more prominent in rats on a high salt diet and are consistent with a contribution of ET
B
-mediated events in the natriuretic response to high salt intake. Taken together, these findings support the hypothesis that endothelin plays an important role in regulating sodium excretion through activation of ET
B
receptors.
NO
−
Activates Soluble Guanylate Cyclase and K
v
Channels to Vasodilate Resistance Arteries
Authors: Irvine Jennifer C. , Favaloro Joanne L. , Kemp-Harper Barbara K.
Published: May 2003

Nitric oxide (NO) plays an important role in the control of vascular tone. Traditionally, its vasorelaxant activity has been attributed to the free radical form of NO (NO
•
), yet the reduced form of NO (NO
−
) is also produced endogenously and is a potent vasodilator of large conduit arteries. The effects of NO
−
in the resistance vasculature remain unknown. This study examines the activity of NO
−
in rat small isolated mesenteric resistance-like arteries and characterizes its mechanism(s) of action. With the use of standard myographic techniques, the vasorelaxant properties of NO
•
(NO gas solution), NO
−
(Angeli’s salt), and the NO donor sodium nitroprusside were compared. Relaxation responses to Angeli’s salt (pEC
50
=7.51±0.13, R
max
=95.5±1.5%) were unchanged in the presence of carboxy-PTIO (NO
•
scavenger) but those to NO
•
and sodium nitroprusside were inhibited.
l
-Cysteine (NO
−
scavenger) decreased the sensitivity to Angeli’s salt (
P
<0.01) and sodium nitroprusside (
P
<0.01) but not to NO
•
. The soluble guanylate cyclase inhibitor ODQ (3 and 10 μmol/L) concentration-dependently inhibited relaxation responses to Angeli’s salt (41.0±6.0% versus control 93.4±1.9% at 10 μmol/L). The voltage-dependent K
+
channel inhibitor 4-aminopyridine (1 mmol/L) caused a 9-fold (
P
<0.01) decrease in sensitivity to Angeli’s salt, whereas glibenclamide, iberiotoxin, charybdotoxin, and apamin were without effect. In combination, ODQ and 4-aminopyridine abolished the response to Angeli’s salt. In conclusion, NO
−
functions as a potent vasodilator of resistance arteries, mediating its response independently of NO
•
and through the activation of soluble guanylate cyclase and voltage-dependent K
+
channels. NO
−
donors may represent a novel class of nitrovasodilator relevant for the treatment of cardiovascular disorders such as angina.
Uric Acid Stimulates Monocyte Chemoattractant Protein-1 Production in Vascular Smooth Muscle Cells Via Mitogen-Activated Protein Kinase and Cyclooxygenase-2
Authors: Kanellis John , Watanabe Susumu , Li Jin H. , Kang Duk Hee , Li Ping , Nakagawa Takahiko , Wamsley Ann , Sheikh-Hamad David , Lan Hui Y. , Feng Lili , Johnson Richard J.
Published: May 2003

Previous studies have reported that uric acid stimulates vascular smooth muscle cell (VSMC) proliferation in vitro. We hypothesized that uric acid may also have direct proinflammatory effects on VSMCs. Crystal- and endotoxin-free uric acid was found to increase VSMC monocyte chemoattractant protein-1 (MCP-1) expression in a time- and dose-dependent manner, peaking at 24 hours. Increased mRNA and protein expression occurred as early as 3 hours after uric acid incubation and was partially dependent on posttranscriptional modification of MCP-1 mRNA. In addition, uric acid activated the transcription factors nuclear factor-κB and activator protein-1, as well as the MAPK signaling molecules ERK p44/42 and p38, and increased cyclooxygenase-2 (COX-2) mRNA expression. Inhibition of p38 (with SB 203580), ERK 44/42 (with UO126 or PD 98059), or COX-2 (with NS398) each significantly suppressed uric acid–induced MCP-1 expression at 24 hours, implicating these pathways in the response to uric acid. The ability of both
n
-acetyl-cysteine and diphenyleneionium (antioxidants) to inhibit uric acid–induced MCP-1 production suggested involvement of intracellular redox pathways. Uric acid regulates critical proinflammatory pathways in VSMCs, suggesting it may have a role in the vascular changes associated with hypertension and vascular disease.
Effects of Endothelin-1 and Endothelin-1 Receptor Blockade on Cardiac Output, Aortic Pressure, and Pulse Wave Velocity in Humans
Authors: Vuurmans Tycho J.L. , Boer Peter , Koomans Hein A.
Published: May 2003

Endothelin-1 (ET-1) is a potent vasoconstrictor. Its effect on arterial wave reflections and central pressure augmentation is unknown. We studied whether ET-1, in plasma concentrations present in disease, increases pulse wave velocity (PWV) and augmentation index (AIx) and therefore compromises cardiac output, and whether the ET-1 receptor blocker VML-588 (previously AXV-034343 and Ro 61–1790) prevents such effects. Nine healthy men received a 2-hour infusion with ET-1 (2.5 ng · kg
−1
· min
−1
) superimposed on vehicle or VML-588 (0.05, 0.20, or 0.40 mg · kg
−1
· h
−1
) (randomized order). Arterial tonometry and pulse wave contour analysis were used to assess aortic PWV and central aortic pressures and impedance cardiography for cardiac output. ET-1 slightly increased mean arterial pressure and peripheral resistance but had no significant effect on systolic blood pressure and pulse pressure. PWV increased from 5.4±0.2 to 5.7±0.3 m/s (
P
<0.05), AIx from 9.9±3.3 to 17.2±3.8 (
P
<0.05), central systolic blood pressure by 8.7±1.7 mm Hg (
P
<0.05), and central pulse pressure by 5.1±1.9 mm Hg (
P
<0.05). This was associated with a fall in cardiac output by ≈18% (
P
<0.05). VML-588 caused a slight decrease in brachial mean arterial pressure, PWV, and AIx, and prevented the effects of ET-1 on central hemodynamics without a clear dose-response effect. In summary, ET-1 in plasma concentrations as found in renal failure and heart failure accelerates PWV, causes a disproportionate increase in central aortic systolic blood pressure and pulse pressure, and decreases cardiac output. These effects can be prevented with an ET-1 receptor blocker such as VML-588. This makes it worthwhile to focus on endothelin as a target to prevent ventricular hypertrophy and to maintain cardiac function in diseases associated with high ET-1.
Early Autonomic Dysfunction in Glucose-Tolerant but Insulin-Resistant Offspring of Type 2 Diabetic Patients
Authors: Frontoni Simona , Bracaglia Daniela , Baroni Alessandra , Pellegrini Fabio , Perna Michela , Cicconetti Elena , Ciampittiello Giuseppina , Menzinger Guido , Gambardella Sergio
Published: May 2003

In type 2 diabetes, both insulin resistance and hyperglycemia are considered responsible for autonomic dysfunction, but the specific role of these two abnormalities is not clear. To test the specific role of insulin resistance on autonomic dysfunction, we studied 69 glucose-tolerant offspring of type 2 diabetic patients, comparing the most insulin-resistant tertile (IR) with the most insulin-sensitive tertile (IS) and comparable control subjects, all undergoing the oral glucose tolerance test, impedentiometry, 24-hour blood pressure and ECG monitoring, and an intravenous glucose tolerance test (IVGTT) followed by a euglycemic hyperinsulinemic clamp, with continuous blood pressure and ECG measurements. Sympathovagal balance was evaluated as low- to high-frequency ratio (LF:HF) by spectral analysis on R-R intervals. The change of systolic and diastolic blood pressure was calculated as [(day-night/d)]×100. In IR, the changes of systolic and diastolic blood pressure were significantly lower versus IS (9.2±5.0% versus 12.4±3.6%,
P
<0.02; 13.2±6.5% versus 17.4±5.2%,
P
<0.02). During the night, LF:HF fall was reduced in IR (43.1±21.0 versus 61.4±16.9,
P
<0.02). Hyperinsulinemia (IVGTT) rapidly and significantly increased LF:HF in IR (4.9±3.3 versus basal: 2.3±1.4,
P
=0.03) but not in IS. In offspring of type 2 diabetic patients with normal glucose tolerance and normal blood pressure values, insulin resistance is associated with abnormal control of blood pressure and sympathetic activation. Insulin resistance may therefore be responsible for some early derangements of the autonomic nervous tone control and thus contributes to increase the incidence of arterial hypertension and/or diabetes.
Classic and Novel Risk Factor Parameters in Women With a History of Preeclampsia
Authors: Sattar Naveed , Ramsay Jane , Crawford Lynne , Cheyne Helen , Greer Ian A.
Published: May 2003

Epidemiological studies demonstrate a relation between preeclampsia (PE) and an increased risk of maternal coronary heart disease (CHD) in later life. However, there are few data available to explain any underlying mechanism. We recruited 40 primigravid women with a history of proteinuric PE delivering between 1975 and 1985 and 40 controls, matched as a group for time of index pregnancy, smoking, and current body mass index to assess classic (lipids, blood pressure) and novel (adhesion molecules, insulin, leptin) risk factor pathways. Women with a history of PE had higher diastolic blood pressure compared with controls (83 vs 76 mm Hg,
P
<0.05), but there were no significant differences in fasting lipoprotein concentrations (
P
>0.20). However, concentrations of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 (ICAM-1) in particular were higher in the PE group by 14% (
P
=0.038) and 44% (
P
=0.002), respectively. The cases also demonstrated a tendency toward higher fasting insulin (
P
=0.08) concentrations and had higher glycosylated hemoglobin levels (
P
=0.004). Leptin concentrations were not significantly elevated. Interestingly, significantly more of the women with history of PE were classified as menopausal (37.55% vs 17.5%,
P
=0.045). The differences in ICAM-1 concentration persisted (
P
=0.010) after adjustment for potential confounders, including hormonal use/menopausal status, antihypertensive or lipid-lowering therapy, and social class. We conclude that classic risk factors alone cannot fully explain the elevated CHD risk in women with a history of PE. Rather markedly elevated ICAM-1 concentrations and specific but subtle features of the metabolic syndrome (glucose, blood pressure) are likely to be involved.
VEGF-D Is the Strongest Angiogenic and Lymphangiogenic Effector Among VEGFs Delivered Into Skeletal Muscle via Adenoviruses
Authors: Rissanen Tuomas T. , Markkanen Johanna E. , Gruchala Marcin , Heikura Tommi , Puranen Antti , Kettunen Mikko I. , Kholová Ivana , Kauppinen Risto A. , Achen Marc G. , Stacker Steven A. , Alitalo Kari , Ylä-Herttuala Seppo
Published: April 2003

Optimal angiogenic and lymphangiogenic gene therapy requires knowledge of the best growth factors for each purpose. We studied the therapeutic potential of human vascular endothelial growth factor (VEGF) family members VEGF-A, VEGF-B, VEGF-C, and VEGF-D as well as a VEGFR-3–specific mutant (VEGF-C
156S
) using adenoviral gene transfer in rabbit hindlimb skeletal muscle. The significance of proteolytic processing of VEGF-D was explored using adenoviruses encoding either full-length or mature (ΔNΔC) VEGF-D. Adenoviruses expressing potent VEGFR-2 ligands, VEGF-A and VEGF-D
ΔNΔC
, induced the strongest angiogenesis and vascular permeability effects as assessed by capillary vessel and perfusion measurements, modified Miles assay, and MRI. The most significant feature of angiogenesis induced by both VEGF-A and VEGF-D
ΔNΔC
was a remarkable enlargement of microvessels with efficient recruitment of pericytes suggesting formation of arterioles or venules. VEGF-A also moderately increased capillary density and created glomeruloid bodies, clusters of tortuous vessels, whereas VEGF-D
ΔNΔC
–induced angiogenesis was more diffuse. Vascular smooth muscle cell proliferation occurred in regions with increased plasma protein extravasation, indicating that arteriogenesis may be promoted by VEGF-A and VEGF-D
ΔNΔC
. Full-length VEGF-C and VEGF-D induced predominantly and the selective VEGFR-3 ligand VEGF-C
156S
exclusively lymphangiogenesis. Unlike angiogenesis, lymphangiogenesis was not dependent on nitric oxide. The VEGFR-1 ligand VEGF-B did not promote either angiogenesis or lymphangiogenesis. Finally, we found a positive correlation between capillary size and vascular permeability. This study compares, for the first time, angiogenesis and lymphangiogenesis induced by gene transfer of different human VEGFs, and shows that VEGF-D is the most potent member when delivered via an adenoviral vector into skeletal muscle.
Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) Expression Is Decreased in Pulmonary Hypertension and Affects Endothelial Cell Growth
Authors: Ameshima Shingo , Golpon Heiko , Cool Carlyne D. , Chan Daniel , Vandivier R. William , Gardai Shyra J. , Wick Marilee , Nemenoff Raphael A. , Geraci Mark W. , Voelkel Norbert F.
Published: April 2003

PPARγ is a member of a family of nuclear receptors/ligand–dependent transcription factors, which bind to hormone response elements on target gene promoters. An antiproliferative and proapoptotic action profile of PPARγ has been described and PPARγ may function as a tumor suppressor gene, but little is known about the role of PPARγ in vascular remodeling. One group of human diseases that shows impressive vascular remodeling exclusively in the lungs is the group of severe pulmonary hypertensive disorders, which is characterized by complex, endothelial cell–proliferative lesions of lung precapillary arterioles composed of clusters of phenotypically altered endothelial cells that occlude the vessel lumen and contribute to the elevation of the pulmonary arterial pressure and reduce local lung tissue blood flow. In the present study, we report the ubiquitous PPARγ expression in normal lungs, and in contrast, a reduced lung tissue PPARγ gene and protein expression in the lungs from patients with severe PH and loss of PPARγ expression in their complex vascular lesions. We show that fluid shear stress reduces PPARγ expression in ECV304 endothelial cells, that ECV304 cells that stably express dominant-negative PPARγ (DN-PPARγ ECV304) form sprouts when placed in matrigel and that DN-PPARγ ECV304 cells, after tail vein injection in nude mice, form lumen-obliterating lung vascular lesions. We conclude that fluid shear stress decreases the expression of PPARγ in endothelial cells and that loss of PPARγ expression characterizes an abnormal, proliferating, apoptosis-resistant endothelial cell phenotype.
Chlamydophila pneumoniae
Induces ICAM-1 Expression in Human Aortic Endothelial Cells via Protein Kinase C–Dependent Activation of Nuclear Factor-κB
Authors: Vielma Silvana A. , Krings Gregor , Lopes-Virella Maria F.
Published: April 2003

Chlamydophila pneumoniae
has an epidemiological link with atherosclerosis and acute cardiovascular events. One mechanism that may explain such a link is the increased expression of intracellular adhesion molecule-1 (ICAM-1) in
C pneumoniae
–infected endothelial cells. Upregulation of ICAM-1 by
C pneumoniae
is well recognized and has been extensively studied, but the signaling pathways involved are not yet defined. Because upregulation of ICAM-1 by cytokines and other stimuli has been shown to be mediated by either mitogen-activated protein kinase, protein kinase C (PKC), or nuclear factor-κB (NF-κB) pathways, we examined whether these pathways were involved in the ICAM-1 upregulation induced by
C pneumoniae
. Our data show a time-dependent phosphorylation of p44/p42 and SAPK/JNK pathways in
C pneumoniae
–infected cells. However, inhibition of the classic mitogen-activated protein kinase pathway using the PD98059 and U0126 inhibitors and inhibition of SAPK/JNK pathway did not suppress
C pneumoniae
–induced ICAM-1 expression.
C pneumoniae
also activates the NF-κB pathway at 30 minutes after infection. Treatment of human aortic endothelial cells (HAECs) with the NF-κB inhibitors BAY117085 and caffeic acid phenethyl ester led to a concentration-dependent inhibition of
C pneumoniae
–induced ICAM-1 upregulation. Finally,
C pneumoniae
–infected HAECs show membrane translocation of total PKC 30 minutes after cell infection. Calphostin C, a general PKC inhibitor, blocked both
C pneumoniae
–induced ICAM-1 expression and
C pneumoniae
–induced NF-κB translocation. In conclusion, we demonstrated that
C pneumoniae
–induced ICAM-1 expression in HAECs requires NF-κB and PKC activation and that NF-κB activation is PKC dependent.
Trends in Stroke and Coronary Heart Disease in the WHO MONICA Project
Authors: Truelsen Thomas , Mähönen Markku , Tolonen Hanna , Asplund Kjell , Bonita Ruth , Vanuzzo Diego
Published: May 2003

Background and Purpose—

Coronary heart disease (CHD) and stroke are leading causes of death and disability. Because they share major common risk factors, it would be expected that trends in mortality and incidence of these 2 major cardiovascular diseases would be similar.

Methods—

Data from the World Health Organization (WHO) Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) Project were used to compare 10-year trends in mortality, event rates, and case fatality from both CHD and stroke. Fifteen populations in the WHO MONICA Project provided data on both CHD (60 763 events) and stroke (10 442 events) in men and women aged 35 to 64 years (23.4 million person-years of observation in total).

Results—

Trends for the 2 cardiovascular diseases varied within and between populations, and when data from all populations were combined, trends in CHD and stroke mortality differed in men (
P
=0.001) but not in women, whereas trends in event rates differed significantly in both men and women (
P
<0.001 and
P
=0.011, respectively). The differences in trends for CHD and stroke case fatality were not statistically significant in either men or women. In sensitivity analyses, differences in trends in event rates remained statistically significant in men (
P
<0.001) but not in women.

Conclusions—

Trends for CHD and stroke mortality rates, event rates, and case fatality differ substantially between and within the study populations.
Revisiting the Appropriateness of Carotid Endarterectomy
Authors: Halm Ethan A. , Chassin Mark R. , Tuhrim Stanley , Hollier Larry H. , Popp A. John , Ascher Enrico , Dardik Herbert , Faust Glenn , Riles Thomas S.
Published: May 2003

Background and Purpose—

In the 1980s, carotid endarterectomy was controversial because proof of efficacy was lacking, complication rates were high, and one third of cases were reported to be inappropriate. Since publication of several randomized controlled trials (RCTs), rates of carotid endarterectomy have doubled nationwide. This study assesses the appropriateness and use of carotid endarterectomy since publication of the RCTs.

Methods—

Using the literature, we developed a list of 1557 mutually exclusive indications for carotid endarterectomy and asked a panel of national experts to rate the appropriateness of each indication using the RAND methodology. We used these ratings to assess appropriateness in a sample of 2124 patients who underwent the procedure in 1997 to 1998 in 6 hospitals. We also analyzed the reasons for the procedure and rates of death, stroke, and myocardial infarction within 30 days of surgery.

Results—

Overall, 84.9% of operations were done for appropriate reasons, 4.5% for uncertain reasons, and 10.6% for inappropriate reasons. Among procedures considered inappropriate, the most common reasons were high comorbidity (46.6%) and minimal stenosis (27.1%). Overall, 72.5% were asymptomatic, 17.4% had a carotid transient ischemic attack, and 10.1% had a stroke. The 30-day rate of death or stroke was 5.47% for symptomatic patients and 2.26% for asymptomatic patients. Among patients having combined carotid and coronary artery bypass graft surgery, the rate was 10.32%. The complication rate in asymptomatic patients with high comorbidity was 5.56%.

Conclusions—

Since the RCTs, rates of overuse appear to have fallen considerably, although they are still significant. A major shift has occurred toward operating on asymptomatic patients. Although overall complication rates were low, rates among asymptomatic patients with high comorbidity exceeded recommended thresholds.
Copper-Zinc Superoxide Dismutase Affects Akt Activation After Transient Focal Cerebral Ischemia in Mice
Authors: Noshita Nobuo , Sugawara Taku , Lewén Anders , Hayashi Takeshi , Chan Pak H.
Published: May 2003

Background and Purpose—

The serine-threonine kinase Akt is activated by phosphorylation at serine-473. After phosphorylation, activated Akt inactivates BAD or caspase-9 or other apoptogenic components, thereby inhibiting cell death. In this study we examined the relationship between Akt phosphorylation and oxidative stress after transient focal cerebral ischemia (FCI) using copper-zinc superoxide dismutase (SOD1) transgenic (Tg) mice.

Methods—

The mice were subjected to 60 minutes of middle cerebral artery occlusion by intraluminal suture blockade followed by 1, 4, and 24 hours of reperfusion. Phospho-Akt expression was examined by immunohistochemistry and Western blot analysis. Production of superoxide anion was assessed by the hydroethidine method in both wild-type mice and SOD1 Tg mice. DNA fragmentation was evaluated by terminal deoxynucleotidyl transferase–mediated uridine 5′-triphosphate-biotin nick end labeling (TUNEL).

Results—

Immunohistochemistry demonstrated that phospho-Akt was constitutively expressed and was decreased in the ischemic core as early as 1 hour after reperfusion, whereas it was temporally increased in the cortex at 4 hours. Phospho-Akt expression was enhanced in the SOD1 Tg mice. Western blot analysis showed that phospho-Akt was maximized 4 hours after reperfusion in the wild-type mice, whereas phospho-Akt was increased as early as 1 hour after ischemia in the SOD1 Tg mice. There was a significant decrease in TUNEL-positive cells in the SOD1 Tg mice compared with the wild-type mice.

Conclusions—

The present study suggests that SOD1 may contribute to the early activation of the Akt cell survival signaling pathway and may attenuate subsequent DNA damage after transient FCI.
Perfusion-Weighted Magnetic Resonance Imaging Thresholds Identifying Core, Irreversibly Infarcted Tissue
Authors: Shih Ludy C. , Saver Jeffrey L. , Alger Jeffry R. , Starkman Sidney , Leary Megan C. , Vinuela Fernando , Duckwiler Gary , Gobin Y. Pierre , Jahan Reza , Villablanca J. Pablo , Vespa Paul M. , Kidwell Chelsea S.
Published: May 2003

Background and Purpose—

Identifying core, irreversibly infarcted tissue and salvageable penumbral tissue is crucial to informed, physiologically guided decision making regarding thrombolytic and other interventional therapies in acute ischemic stroke. Pretreatment perfusion MRI offers promise as a means to differentiate core from penumbral tissues.

Methods—

Diffusion-perfusion MRIs were performed before treatment and on day 7 in patients undergoing successful vessel recanalization with intra-arterial thrombolytic therapy. Perfusion maps of the time to peak of the residue function (T
max
) were generated after deconvolution of an arterial input function. Initial perfusion abnormalities and final infarct regions were outlined by hand. Posttreatment images were coregistered to the pretreatment study. Voxel-by-voxel and volume analyses were performed to identify thresholds of perfusion abnormalities that best predict core, irreversibly infarcted tissue.

Results—

Fourteen patients (4 men, 10 women) with vessel recanalization were studied. Mean age was 73 years, and median entry National Institutes of Health Stroke Scale score was 12. Mean time from symptom onset to start of intra-arterial infusion was 245 minutes and to recanalization was 338 minutes. With a voxel-by-voxel analysis, T
max
≥6 and ≥8 seconds (sensitivity, 71% and 53%; specificity, 63% and 80%) correlated most highly with day 7 final infarct. With a volume analysis, T
max
≥6 and ≥8 seconds (
r
2
=0.704 and
r
2
=0.705) correlated most highly with day 7 final infarct.

Conclusions—

Perfusion-weighted imaging measures of ischemia severity accurately differentiate irreversibly injured core from penumbral, salvageable tissue. The best threshold for identifying core infarcted tissue is adjusted T
max
of ≥6 to 8 seconds.
Effects of Form Familiarity on Perception of Words, Pseudowords, and Nonwords in the Two Cerebral Hemispheres
Authors: Jordan Timothy R. , Redwood Michelle , Patching Geoffrey R.
Published: May 2003

Previous investigations of hemispheric processes of word perception provide a mixed picture of the sensitivity of each hemisphere to the familiarity of the visual form of lateralized displays. We investigated this issue by presenting words, pseudowords, and nonwords briefly to either the left (LH) or right (RH) hemisphere in lowercase, uppercase, and a matched, unfamiliar mixed-case form, and used an eye tracker to ensure central fixation and the Reicher–Wheeler task to suppress influences of stimulus asymmetry. Familiarity of form exerted a substantial effect on perception. In particular, perception of LH and RH displays of words, pseudowords, and nonwords was least accurate for mixed case, intermediate for upper case, and most accurate for lowercase. However, form had no effect on the LH advantage observed for words, pseudowords, and nonwords, indicating that form affected processing in both hemispheres to a similar extent. Moreover, LH and RH displays both showed that mixed case disrupted performance most for words, and more for pseudowords than for nonwords, indicating the sensitivity to form shown by each hemisphere reflected more than a general perceptual process. Implications for the role of form familiarity in hemispheric processing of words are discussed.