bluuebunny/crossref_metadata_2025 huggingface dataset:
Autocrine Regulation of Myocyte Cx43 Expression by VEGF
Authors: Pimentel Rhea C. , Yamada Kathryn A. , Kléber André G. , Saffitz Jeffrey E.
Published: July 2002

Cardiac myocytes can rapidly adjust their expression of gap junction channel proteins in response to changes in load. Previously, we showed that after only 1 hour of linear pulsatile stretch (110% of resting cell length; 3 Hz), expression of connexin43 (Cx43) by cultured neonatal rat ventricular myocytes is increased by ≈2-fold and impulse propagation is significantly more rapid. In the present study, we tested the hypothesis that vascular endothelial growth factor (VEGF), acting downstream of transforming growth factor-β (TGF-β), mediates stretch-induced upregulation of Cx43 expression by cardiac myocytes. Incubation of nonstretched cells with exogenous VEGF (100 ng/mL) or TGF-β (10 ng/mL) for 1 hour increased Cx43 expression by ≈1.8-fold, comparable to that observed in cells subjected to pulsatile stretch for 1 hour. Stretch-induced upregulation of Cx43 expression was blocked by either anti-VEGF antibody or anti-TGF-β antibody. Stretch-induced enhancement of conduction was also blocked by anti-VEGF antibody. ELISA assay showed that VEGF was secreted into the culture medium during stretch. Furthermore, stretch-conditioned medium stimulated Cx43 expression in nonstretched cells. This effect was also blocked by anti-VEGF antibody. Upregulation of Cx43 expression stimulated by exogenous TGF-β was blocked by anti-VEGF antibody, but VEGF-stimulation of Cx43 expression was not blocked by anti-TGF-β antibody. Thus, stretch-induced upregulation of Cx43 expression is mediated, at least in part, by VEGF, which acts downstream of TGF-β. Because the cultures contained only ≈5% nonmyocytic cells, these results indicate that myocyte-derived VEGF, secreted in response to stretch, acts in an autocrine fashion to enhance intercellular coupling.
Different Signaling Pathways Induce Apoptosis in Endothelial Cells and Cardiac Myocytes During Ischemia/Reperfusion Injury
Authors: Scarabelli Tiziano M. , Stephanou Anastasis , Pasini Evasio , Comini Laura , Raddino Riccardo , Knight Richard A. , Latchman David S.
Published: July 2002

Apoptosis contributes, with necrosis, to the cardiac cell loss after ischemia/reperfusion injury. The apoptotic cascade is initiated either by mitochondrial damage and activation of caspase-9 or by death receptor ligation and activation of caspase-8. In the present study, performed in the isolated rat heart exposed either to ischemia alone or ischemia followed by reperfusion, cleavage of caspase-9 was observed primarily in endothelial cells. Conversely, caspase-8 cleavage was only found in cardiomyocytes, where it progressively increased throughout reperfusion. Addition of a specific caspase-9 inhibitor to the perfusate before ischemia prevented endothelial apoptosis, whereas preischemic infusion of a specific caspase-8 inhibitor affected only myocyte apoptosis. Additionally, caspase-8–mediated BID processing was observed only during reperfusion. Production of tBID then sustains mitochondrial injury and perpetuates caspase-9 activation.
CD36 Mediates the Cardiovascular Action of Growth Hormone-Releasing Peptides in the Heart
Authors: Bodart V. , Febbraio M. , Demers A. , McNicoll N. , Pohankova P. , Perreault A. , Sejlitz T. , Escher E. , Silverstein R.L. , Lamontagne D. , Ong H.
Published: July 2002

Growth hormone-releasing peptides (GHRPs) are known as potent growth hormone secretagogues whose actions are mediated by the ghrelin receptor, a G protein-coupled receptor cloned from pituitary libraries. Hexarelin, a hexapeptide of the GHRP family, has reported cardiovascular activity. To identify the molecular target mediating this activity, rat cardiac membranes were labeled with a radioactive photoactivatable derivative of hexarelin and purified using lectin affinity chromatography and preparative gel electrophoresis. A binding protein of M
r
84 000 was identified. The N-terminal sequence determination of the deglycosylated protein was identical to rat CD36, a multifunctional glycoprotein, which was expressed in cardiomyocytes and microvascular endothelial cells. Activation of CD36 in perfused hearts by hexarelin was shown to elicit an increase in coronary perfusion pressure in a dose-dependent manner. This effect was lacking in hearts from CD36-null mice and hearts from spontaneous hypertensive rats genetically deficient in CD36. The coronary vasoconstrictive response correlated with expression of CD36 as assessed by immunoblotting and covalent binding with hexarelin. These data suggest that CD36 may mediate the coronary vasospasm seen in hypercholesterolemia and atherosclerosis.
Reduced Atherosclerotic Plaque but Enhanced Aneurysm Formation in Mice With Inactivation of the Tissue Inhibitor of Metalloproteinase-1 (
TIMP-1
) Gene
Authors: Silence J. , Collen D. , Lijnen H.R.
Published: July 2002

Development and progression of atherosclerotic lesions and aneurysm formation were investigated in mice with single or combined deficiency of apolipoprotein E (ApoE) and tissue inhibitor of metalloproteinase-1 (TIMP-1) kept on a cholesterol-rich diet for 30 weeks. Atherosclerotic lesions throughout the thoracic aorta were significantly (
P
<0.001) larger in mice wild-type for TIMP-1 (ApoE
−/−
:TIMP-1
+/+
) than in mice deficient in TIMP-1 (ApoE
−/−
:TIMP-1
−/−
). Aneurysms in the thoracic and abdominal aortas were less frequent in ApoE
−/−
:TIMP-1
+/+
mice than in ApoE
−/−
:TIMP-1
−/−
mice (11±3.0 versus 23±5.1 aneurysms per 100 sections analyzed, mean±SD,
P
<0.001). Immunocytochemistry revealed enhanced accumulation of Oil red O–stained lipids, colocalizing with macrophages in atherosclerotic lesions of ApoE
−/−
:TIMP-1
−/−
mice (
P
<0.05). In situ zymography using a casein substrate showed enhanced lysis in plaques of ApoE
−/−
:TIMP-1
−/−
mice as compared with ApoE
−/−
:TIMP-1
+/+
mice (
P
<0.01). MMP activity was most pronounced at sites where degradation of the elastic lamina occurred. These data suggest that enhanced MMP activity, as a result of TIMP-1 deficiency, contributes to a reduction of atherosclerotic plaque size but promotes aneurysm formation.
Inhibition of p38 MAPK Activation via Induction of MKP-1
Authors: Kiemer Alexandra K. , Weber Nina C. , Fürst Robert , Bildner Nicole , Kulhanek-Heinze Stefanie , Vollmar Angelika M.
Published: July 2002

The atrial natriuretic peptide (ANP) is a cardiovascular hormone possessing antiinflammatory potential due to its inhibitory action on the production of inflammatory mediators, such as tumor necrosis factor-α (TNF-α). The aim of this study was to determine whether ANP is able to attenuate inflammatory effects of TNF-α on target cells. Human umbilical vein endothelial cells (HUVECs) were treated with TNF-α in the presence or absence of ANP. Changes in permeability, cytoskeletal alterations, phosphorylation of p38 MAPK and HSP27, and expression of MKP-1 were determined by macromolecule permeability assay, fluorescence labeling, RT-PCR, and immunoblotting. Antisense studies were done by transfecting cells with MKP-1 antisense oligonucleotides. Activation of HUVECs with TNF-α lead to a significant increase of macromolecule permeability and formation of stress fibers. Treatment of cells with ANP (10
−8
to 10
−6
mol/L) significantly reduced the formation of stress fibers and elevated permeability. Both TNF-α–induced effects were shown to be mediated via the activation of p38 using SB203580, a specific inhibitor of p38. ANP significantly reduced the TNF-α–induced activation of p38 and attenuated the phosphorylation of HSP27, a central target downstream of p38. ANP showed no effect on p38 upstream kinases MKK3/6. However, a significant induction of the MAPK phosphatase MKP-1 mRNA and protein could be observed in ANP-treated cells. Antisense experiments proved a causal role for MKP-1 induction in the ANP-mediated inhibition of p38. These data show the inhibitory action of ANP on TNF-α–induced changes in endothelial cytoskeleton and macromolecule permeability involving an MKP-1–induced inactivation of p38 MAPK. These effects point to an antiinflammatory and antiatherogenic potential of this cardiovascular hormone.
Mutation in the ARH Gene and a Chromosome 13q Locus Influence Cholesterol Levels in a New Form of Digenic-Recessive Familial Hypercholesterolemia
Authors: Al-Kateb Hussam , Bähring Sylvia , Hoffmann Katrin , Strauch Konstantin , Busjahn Andreas , Nürnberg Gudrun , Jouma Muhidien , Bautz Eckehard K.F. , Dresel Hans A. , Luft Friedrich C.
Published: July 2002

We studied a Syrian family with 3 children who had low-density lipoprotein cholesterol (LDL) concentrations of 13.3, 12.2, and 8.6 mmol/L, respectively. Three other siblings and the parents all had LDL values <4.52 mmol/L, suggesting an autosomal-recessive mode of inheritance. The extended pedigree had 66 additional persons with normal LDL values. A genome-wide scan in the core family with 427 markers showed support for linkage on both chromosomes 1 and 13. Markers on chromosome 1 revealed a 3.07 multipoint LOD score between 1p36.1-p35, an 18-cM interval. Surprisingly, we also found linkage to 13q22-q32, a 14-cM interval, with a 3.08 LOD score. We had identified this locus earlier as containing a gene strongly influencing LDL in another Arab family with autosomal-dominant familial hypercholesterolemia and in normal dizygotic twins. We found evidence for an interaction between these loci. We next genotyped our twin panel and confirmed linkage of the 1p36.1-p35 locus to LDL (
P
<0.002) in this normal population. Elucidation of ARH, the LDL receptor adaptor protein at chromosome 1p35, caused us to sequence that gene. We first identified the genomic structure of ARH gene and then sequenced the gene in our family. We found an intron 1 acceptor splice-site mutation. This mutation was not found in any other family members, in 31 nonrelated Syrian persons, or in 30 Germans. Our results underscore the importance of ARH on chromosome 1 and the chromosome 13q locus to LDL, not only in families with unusual illnesses, but also to the general population.
Thioredoxin Promotes ASK1 Ubiquitination and Degradation to Inhibit ASK1-Mediated Apoptosis in a Redox Activity-Independent Manner
Authors: Liu Yingmei , Min Wang
Published: July 2002

It has been shown that thioredoxin (Trx) in a reduced form binds to and inhibits apoptosis signal-regulating kinase 1 (ASK1). Apoptotic stimuli such as tumor necrosis factor (TNF) and reactive oxygen species (ROS) activate ASK1 in part by oxidizing Trx (forming intramolecular disulfide between C32 and C35) to release Trx from ASK1. In the present study, we examined if Trx affects ASK1 protein stability and whether the redox activity of Trx is critical in regulating ASK1 activity. First, we showed that overexpression of the wild-type Trx (Trx-WT) in endothelial cells induced ASK1 ubiquitination and degradation. Trx-induced ASK1 ubiquitination/degradation could be blocked by ASK1 activators TNF and TRAF2. We then tested the single-mutation of Trx at the catalytic site C32 or C35 (Trx-C32S or Trx-C35S) and the double-mutation (Trx-CS). The results showed that the single mutants (but not Trx-CS) retained the binding activity for ASK1 and the ability to induce ASK1 ubiquitination/degradation. Unlike Trx-WT, Trx-C32S and Trx-C35S mutants constitutively bind to ASK1 even in the presence of hydrogen peroxide in vitro and TNF in vivo. Finally, we showed that the single mutants (not Trx-WT) significantly (n=4 and
P
<0.05) inhibited ASK1-induced JNK activation, caspase 3 activity, and apoptosis in TNF/ROS-resistant manner. Our data suggest that association of Trx with ASK1 through a single Cysteine (C32 or C35) is necessary and sufficient for Trx activity in inducing ASK1 ubiquitination/degradation leading to inhibition of ASK1-induced apoptosis.
Glycated Collagen I Induces Premature Senescence-Like Phenotypic Changes in Endothelial Cells
Authors: Chen Jun , Brodsky Sergey V. , Goligorsky David M. , Hampel Dierk J. , Li Hong , Gross Steven S. , Goligorsky Michael S.
Published: July 2002

Diabetic vasculopathy is central to the development of diverse cardiovascular, renal, retinal, and neurological complications of diabetes. We previously demonstrated that growth of endothelial cells on glycated extracellular matrix proteins (collagen and matrigel) results in a significant decrease in cell proliferation. In the present study, we show that early-passage human umbilical vein endothelial cells (HUVECs) grown on glycated collagen (GC) express hallmarks of premature cell senescence, ie, increase in the proportion of cells expressing senescence-associated β-galactosidase activity, apoptotic rate, and p53 and p14
AFR
expression, but in contrast to replicative senescence, display neither attrition of telomeres nor decrease in telomerase activity. An increased frequency of prematurely senescent cells was similarly observed in vivo in aortae of young Zucker diabetic rats, compared with lean controls. NO production by HUVECs grown on GC was decreased, despite a 3-fold increase in eNOS expression and was associated with the increased nitrotyrosine-modified proteins. Development of premature senescence of HUVECs on GC could be prevented and reversed by treatments with the peroxynitrite scavenger, ebselen, eNOS intermediate

N
ω

-hydroxy-
l
-arginine (NOHA), or superoxide dismutase mimetic Mn-TBAP. Concomitant with the reversal of senescence, ebselen, and NOHA each restored NO production to levels observed with HUVECs grown on unmodified collagen. Our findings indicate that diabetes mellitus in vivo and GC exposure in vitro elicit premature senescence of the vascular endothelium, a process with distinct pathogenetic mechanisms. Premature senescence of the vascular endothelium is hypothesized to be an important contributor to diabetic vasculopathy and a consequence of reduced NO availability, peroxynitrite, and/or superoxide excess.
Inhibitory Effects of Novel AP-1 Decoy Oligodeoxynucleotides on Vascular Smooth Muscle Cell Proliferation In Vitro and Neointimal Formation In Vivo
Authors: Ahn Jong Deok , Morishita Ryuichi , Kaneda Yasufumi , Lee Sang-Jun , Kwon Ki-Young , Choi Se-Young , Lee Ki-Up , Park Joong-Yeol , Moon Ik-Jae , Park Jong-Gu , Yoshizumi Masao , Ouchi Yasuyoshi , Lee In-Kyu
Published: July 2002

Excessive proliferation of vascular smooth muscle cells (VSMCs) and neointimal formation are critical steps in the pathogenesis of atherosclerosis and restenosis after percutaneous transluminal angioplasty. In this study, we investigated the hypothesis that the activator protein-1 (AP-1) plays an important role in neointimal formation after vascular injury. A circular dumbbell AP-1 decoy oligodeoxynucleotide (CDODN) was developed as a novel therapeutic strategy for restenosis after angioplasty. This CDODN was more stable than the conventional phosphorothioate linear decoy ODN (PSODN) and maintained structural integrity on exposure to exonuclease III or serum. Transfection with AP-1 decoy ODNs strongly inhibited VSMC proliferation and migration, as well as glucose- and serum-induced expression of PCNA and cyclin A genes. Administration of AP-1 decoy ODNs in vivo using the hemagglutinating virus of Japan (HVJ)-liposome method virtually abolished neointimal formation after balloon injury to the rat carotid artery. Compared with PSODN, CDODN was more effective in inhibiting the proliferation of VSMCs in vitro and neointimal formation in vivo. Our results collectively indicate that AP-1 activation is crucial for the mediation of VSMC proliferation in response to vascular injury. Moreover, the use of stable CDODN specific for AP-1 activity in combination with the highly effective HVJ-liposome method provides a novel potential therapeutic strategy for the prevention of restenosis after angioplasty in humans.
GFP-FRNK Disrupts Focal Adhesions and Induces Anoikis in Neonatal Rat Ventricular Myocytes
Authors: Heidkamp Maria C. , Bayer Allison L. , Kalina Jared A. , Eble Diane M. , Samarel Allen M.
Published: July 2002

Focal adhesion kinase (FAK) is a nonreceptor protein tyrosine kinase involved in adhesion-dependent signal transduction. FAK is highly expressed in cultured neonatal rat ventricular myocytes (NRVMs) and undergoes tyrosine autophosphorylation in response to cell adhesion, stretch, and growth factor stimulation. We previously showed that inhibition of FAK phosphorylation by adenovirally mediated overexpression of FRNK (the autonomously expressed C-terminal domain of FAK) prevented endothelin-1 (ET)-induced NRVM hypertrophy. One question raised by these studies was whether FRNK localized to focal adhesions and displaced FAK from sites required for downstream signaling. Therefore, we constructed a replication-defective adenovirus encoding a GFP-FRNK fusion protein (Adv-GFP-FRNK) and examined its effects on NRVM cytoarchitecture and signaling. Uninfected NRVMs contained small amounts of endogenous FRNK. NRVMs infected with Adv-GFP-FRNK expressed much larger amounts of a 66-/68-kDa protein that localized to costameres and focal adhesions. GFP-FRNK overexpression suppressed basal and ET-induced FAK phosphorylation and also inhibited ET-induced phosphorylation of PYK2, the other member of the FAK family of nonreceptor protein tyrosine kinases. In contrast, GFP-FRNK overexpression did not prevent ET-induced ERK, JNK, or p70S6K phosphorylation. Furthermore, GFP-FRNK resulted in the loss of detectable FAK and paxillin in focal adhesions, which was accompanied by reduced levels of total paxillin and, ultimately, cell detachment and apoptosis. We conclude that FRNK functions as a dominant-negative inhibitor of adhesion-dependent signaling by displacing FAK from focal adhesions and interfering with the anchorage of NRVMs that is necessary for cell survival, a process known as anoikis.
Renal Myogenic Response
Authors: Loutzenhiser Rodger , Bidani Anil , Chilton Lisa
Published: July 2002

The kinetic attributes of the afferent arteriole myogenic response were investigated using the in vitro perfused hydronephrotic rat kidney. Equations describing the time course for pressure-dependent vasoconstriction and vasodilation, and steady-state changes in diameter were combined to develop a mathematical model of autoregulation. Transfer functions were constructed by passing sinusoidal pressure waves through the model. These findings were compared with results derived using data from instrumented conscious rats. In each case, a reduction in gain and increase in phase were observed at frequencies of 0.2 to 0.3 Hz. We then examined the impact of oscillating pressure signals. The model predicted that pressure signals oscillating at frequencies above the myogenic operating range would elicit a sustained vasoconstriction the magnitude of which was dependent on peak pressure. These predictions were directly confirmed in the hydronephrotic kidney. Pressure oscillations presented at frequencies of 1 to 6 Hz elicited sustained afferent vasoconstrictions and the magnitude of the response depended exclusively on the peak pressure. Elevated systolic pressure elicited vasoconstriction even if mean pressure was reduced. These findings challenge the view that the renal myogenic response exists to maintain glomerular capillary pressure constant, but rather imply a primary role in protecting against elevated systolic pressures. Thus, the kinetic features of the afferent arteriole allow this vessel to adjust tone in response to changes in systolic pressures presented at the pulse rate. We suggest that the primary function of this mechanism is to protect the glomerulus from the blood pressure power that is normally present at the pulse frequency.
Hypoxia-Reoxygenation
Authors: Hung Tai-Ho , Skepper Jeremy N. , Charnock-Jones D. Stephen , Burton Graham J.
Published: July 2002

Preeclampsia is a severe disorder of human pregnancy characterized by generalized activation of maternal endothelial cells. Oxidative stress of the placenta is considered a key intermediary step, precipitating deportation of apoptotic fragments into the maternal circulation, but the cause remains unknown. We hypothesize that intermittent placental perfusion, secondary to deficient trophoblast invasion of the endometrial arteries, leads to an ischemia-reperfusion–type insult. We therefore tested whether hypoxia-reoxygenation (H/R) in vitro stimulates apoptosis in human placental tissues compared with controls kept hypoxic or normoxic throughout. After H/R, release of cytochrome
c
from mitochondria was significantly increased and was associated with intense immunolabeling for active caspase 3 in the syncytiotrophoblast and fetal endothelial cells. There was also increased labeling of syncytiotrophoblastic nuclei for cleaved poly (ADP-ribose) polymerase (PARP), and higher cytosolic concentrations of cleaved PARP fragment were detected by Western blot. Syncytiotrophoblastic nuclei displayed increased chromatin condensation, and a significantly greater percentage was TUNEL positive. These changes were accompanied by increased lactate dehydrogenase release into the medium. Preadministration of the free radical scavenger, desferrioxamine, reduced cytochrome
c
release and the TUNEL-positive index, suggesting generation of hydroxyl radicals mediates these processes. By contrast, hypoxia alone caused a smaller increase in the TUNEL-positive index, and the majority of syncytiotrophoblastic nuclei displayed karyolysis, whereas normoxic controls remained euchromatic. We conclude that H/R stimulates apoptotic changes within the syncytiotrophoblast, whereas hypoxia principally induces necrosis. The quality of placental perfusion may therefore be a more important factor in the pathophysiology of preeclampsia than the absolute quantity.
Well-Being After Stroke in Canadian Seniors
Authors: Clarke Philippa , Marshall Victor , Black Sandra E. , Colantonio Angela
Published: July 2002

Background and Purpose

—

After a stroke many people continue to live with their residual impairments and disabilities in the community, which can pose a significant problem for survivors’ well-being. The purpose of this research was to investigate patterns of well-being in community-dwelling stroke survivors to identify those factors that restrict and enhance well-being.

Methods

—

A secondary analysis was conducted on data from the second wave of the Canadian Study of Health and Aging (CSHA-2). A national sample of 5395 community-dwelling Canadian seniors (aged ≥65 years) was interviewed for CSHA-2, including 339 stroke survivors (6.3%). Information was collected on health, social and demographic characteristics, and well-being. Comparisons were made between the health and functional status of stroke survivors and community-dwelling seniors who have not experienced a stroke. Multiple regression was used to examine the factors associated with well-being in stroke survivors.

Results

—

Compared with community-dwelling seniors who have not experienced a stroke, stroke survivors report a lower sense of well-being. Stroke survivors are also more likely to be restricted in their physical and cognitive function, to report worse mental health, and to be living with a greater number of comorbid health conditions. Mental health and physical and cognitive disabilities are associated with a reduced sense of well-being in stroke survivors, but social supports and educational resources moderate the impact of functional status on well-being.

Conclusions

—

Community-dwelling seniors who have had a stroke experience a reduced sense of well-being. However, social resources can help to alleviate the subjective burden of this common neurological condition.
Risk of Stroke, Transient Ischemic Attack, and Vessel Occlusion Before Endarterectomy in Patients With Symptomatic Severe Carotid Stenosis
Authors: Blaser Till , Hofmann Katrin , Buerger Thomas , Effenberger Olaf , Wallesch Claus-Werner , Goertler Michael
Published: July 2002

Background and Purpose

—

We aimed to identify and determine the clinical relevance of parameters predictive of stroke recurrence and vessel occlusion before carotid endarterectomy.

Methods

—

One hundred forty-three consecutive patients (105 men; mean age, 66.1±8 years) with symptomatic severe carotid artery stenosis were prospectively followed up until carotid endarterectomy. Patients had suffered an ischemic vascular event in the ipsilateral anterior circulation 9.6 days (median; range, 0 to 92 days) before presentation and assessment of stenosis. Admission examination included medical history, neurological status, extracranial and transcranial Doppler/duplex sonography, CT/MRI, ECG, and routine laboratory examination. All patients were reevaluated in the same way the day before surgery (without CT/MRI) and at recurrence of an ischemic event (including CT/MRI).

Results

—

The end point of follow-up after 19.0 days (median; range, 0 to 118) was carotid endarterectomy in 120 patients, ipsilateral recurrent ischemia in 15 patients (7 transient events and 8 disabling strokes, with carotid occlusion in 4), and (asymptomatic) carotid occlusion in 8 patients. An exhausted cerebrovascular reactivity as determined by a Doppler CO
2
test in the middle cerebral artery ipsilateral to the stenosis was the only independent predictive parameter for disabling stroke (odds ratio [OR], 9.7; 95% confidence interval [CI], 2.1 to 44.1;
P
=0.003). Stroke rate in patients with exhausted reactivity was 27% per month compared with 5.2% in those with normal reactivity. Progression of stenosis toward occlusion was observed in 12 patients and correlated with decreased poststenotic peak systolic velocity (OR, 0.75; 95% CI, 0.62 to 0.90;
P
=0.002), poststenotic arterial narrowing (OR, 22.7; 95% CI, 3.6 to 141.6;
P
=0.001), and very severe stenosis (OR, 13.6; 95% CI, 2.2 to 83.7;
P
=0.005). In patients without hemodynamic compromise, occlusion was not associated with increased stroke risk.

Conclusions

—

Patients with recently symptomatic high-grade carotid artery stenosis and ipsilateral hemodynamic compromise are at high risk for early disabling stroke. Assessment of the hemodynamic status is recommended after diagnosis of severe carotid stenosis in symptomatic patients to further investigate and evaluate whether these patients may benefit from early endarterectomy.
Bone Formation in Carotid Plaques
Authors: Hunt Jennifer L. , Fairman Ronald , Mitchell Marc E. , Carpenter Jeffrey P. , Golden Michael , Khalapyan Tigran , Wolfe Megan , Neschis David , Milner Ross , Scoll Benjamin , Cusack Anita , Mohler Emile R.
Published: July 2002

Background and Purpose

—

Bone formation and dystrophic calcification are present in carotid endarterectomy plaques. The clinical significance of these findings is unknown. The purpose of this study was to determine whether bone formation and extensive dystrophic calcification are associated with stable plaques and protective against ischemic vascular events.

Methods

—

Carotid endarterectomy plaques were collected from 142 patients (94 men) with carotid stenosis. The specimens were evaluated for lamellar bone formation, dystrophic calcifications, inflammatory infiltrates, neovascularization, and histological type or grade of plaque according to a standard AHA grading system. Immunohistochemical staining was performed to identify vascular endothelial cells in neovascularization (factor VIII) and lymphocytes. Clinical data, including history of cerebrovascular and cardiovascular events, were recorded at the time of surgery.

Results

—

Patients with calcification of carotid plaques had fewer symptoms of stroke and transient ischemic attack (
P
=0.042) than those without calcification. Stroke and transient ischemic attack occurred less frequently in patients with plaques with large calcific granules (
P
=0.021). Of the patients, 13% had lamellar bone formation, which directly correlated with the presence of sheetlike calcifications (
P
=0.0001) and inversely correlated with ulcerated lesions (
P
=0.048). The presence of bone also correlated with diabetes (
P
<0.01) and coronary artery disease (
P
<0.01). Of the 20 patients with bone, 6 had a history of stoke and transient ischemic attack (
P
=0.5).

Conclusions

—

The results indicate that bone formation tends to occur in heavily calcified carotid lesions devoid of ulceration and hemorrhage. Patients with extensive calcification of the carotid plaques are less likely to have symptomatic disease.
NAP, a Femtomolar-Acting Peptide, Protects the Brain Against Ischemic Injury by Reducing Apoptotic Death
Authors: Leker Ronen R. , Teichner Angella , Grigoriadis Nikolas , Ovadia Haim , Brenneman Douglas E. , Fridkin Mati , Giladi Eli , Romano Jacob , Gozes Illana
Published: July 2002

Background and Purpose

—

We sought to determine the cerebroprotective potential of NAP, a synthetic octapeptide related to vasoactive intestinal peptide. Activity-dependent neuroprotective protein mediates some of the protective effects of vasoactive intestinal peptide. The neuroprotective NAP sequence is derived from activity-dependent neuroprotective protein.

Methods

—

Spontaneously hypertensive rats underwent permanent middle cerebral artery occlusion by craniotomy and electrocoagulation. After dose-response and time-course experiments, the animals were injected with NAP (3 μg/kg) or vehicle intravenously 1 hour after stroke onset. Another group of rats was injected with the
d
-amino acid isomer of NAP (D-NAP) and served as a negative control. Rats were examined for motor and behavioral deficits 24 hours to 30 days later, and infarct volumes were determined. The effect of NAP administration on apoptotic death was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and caspase-3 stainings.

Results

—

NAP significantly reduced motor disability and infarct volumes compared with vehicle or D-NAP when tested at 24 hours after stroke onset (9.67±1.4% versus 17.04±1.18% and 19.19±1.9% of hemispheric volume, respectively;
P
<0.05). NAP given 4 but not 6 hours after permanent middle cerebral artery occlusion still conferred significant neuroprotection (infarct volume 10.9±3.9% of hemispheric volume;
P
<0.05 versus vehicle). Long-term studies demonstrated that infarct volumes and disability scores remained significantly lower after 30 days in NAP-treated animals. NAP significantly reduced the number of apoptotic cells.

Conclusions

—

Our results indicate that the durable cerebroprotection by NAP involves antiapoptotic mechanisms.
Cellular Responses of Bioabsorbable Polymeric Material and Guglielmi Detachable Coil in Experimental Aneurysms
Authors: Murayama Yuichi , Viñuela Fernando , Tateshima Satoshi , Gonzalez Nestor R. , Song Joon K. , Mahdavieh Haleh , Iruela-Arispe Luisa
Published: July 2002

Background and Purpose

—

Acceleration of healing mechanisms is a promising approach to improve current limitations of endovascular aneurysm therapy with the use of platinum coils. We evaluated a new endovascular therapeutic, bioabsorbable polymeric material (BPM), which may promote cellular reaction in the aneurysms.

Methods

—

Four different concentrations of lactide/glycolic acid copolymer [poly(
d
-
l
-lactic-co-glycolic acid)] (PLGA), 85/15, 75/25, 65/35, and 50/50, were used as BPMs. Sixteen experimental aneurysms were created in 8 swine. Eight-millimeter-long spiral-shaped BPMs were surgically implanted in the aneurysms without tight packing (n=3 for each BPM). Guglielmi detachable coils (GDCs) were used as control (n=4). The animals were killed 14 days after embolization, and angiographic, histological, and immunohistochemical analyses were performed.

Results

—

Despite loose packing of aneurysms with BPMs, faster BPMs such as 50/50 or 65/35 PLGA demonstrated more mature collagen formation and fibrosis in the sac and neck of the aneurysm. One aneurysm treated with 65/35 PLGA, 1 treated with 75/25 PLGA, and all 3 treated with 85/15 PLGA showed a neck remnant on angiography. There was a linear relationship between collagen levels and polymer degradation properties (
r
=−0.9513).

Conclusions

—

This preliminary animal study indicates that acceleration of aneurysm healing with the use of BPM is feasible. This concept can be applied to decrease and perhaps prevent aneurysmal recanalization after endovascular treatment of cerebral aneurysms.
Blood Pressure and Clinical Outcomes in the International Stroke Trial
Authors: Leonardi-Bee Jo , Bath Philip M.W. , Phillips Stephen J. , Sandercock Peter A.G.
Published: July 2002

Background and Purpose

—

Among patients with acute stroke, high blood pressure is often associated with poor outcome, although the reason is unclear. We analyzed data from the International Stroke Trial (IST) to explore the relationship between systolic blood pressure (SBP), subsequent clinical events over the next 2 weeks, and functional outcome at 6 months in patients with acute stroke.

Methods

—

We included in the analysis 17 398 patients from IST with confirmed ischemic stroke. A single measurement of SBP was made immediately before randomization. Clinical events within 14 days of randomization were recorded: recurrent ischemic stroke, symptomatic intracranial hemorrhage, death resulting from presumed cerebral edema, fatal coronary heart disease, and death. Survival and dependency were assessed at 6 months. Outcomes were adjusted for age, sex, clinical stroke syndrome, time to randomization, consciousness level, atrial fibrillation, and treatment allocation (aspirin, unfractionated heparin, both, or neither).

Results

—

A U-shaped relationship was found between baseline SBP and both early death and late death or dependency: early death increased by 17.9% for every 10 mm Hg below 150 mm Hg (
P
<0.0001) and by 3.8% for every 10 mm Hg above 150 mm Hg (
P
=0.016). The rate of recurrent ischemic stroke within 14 days increased by 4.2% for every 10–mm Hg increase in SBP (
P
=0.023); this association was present in both fatal and nonfatal recurrence. Death resulting from presumed cerebral edema was independently associated with high SBP (
P
=0.004). No relationship between symptomatic intracranial hemorrhage and SBP was seen. Low SBP was associated with a severe clinical stroke (total anterior circulation syndrome) and an excess of deaths from coronary heart disease (
P
=0.002).

Conclusions

—

Both high blood pressure and low blood pressure were independent prognostic factors for poor outcome, relationships that appear to be mediated in part by increased rates of early recurrence and death resulting from presumed cerebral edema in patients with high blood pressure and increased coronary heart disease events in those with low blood pressure. The occurrence of symptomatic intracranial hemorrhage within 14 days was independent of SBP.
Clinical Course of Cranial Dural Arteriovenous Fistulas With Long-Term Persistent Cortical Venous Reflux
Authors: van Dijk J. Marc C. , terBrugge Karel G. , Willinsky Robert A. , Wallace M. Christopher
Published: July 2002

Background and Purpose

—

The natural history of aggressive (Borden 2 and 3) cranial dural arteriovenous fistulas (DAVFs) is not well described. Reported annual mortality and hemorrhage rates vary widely and range up to 20% per year. A consecutive single-center cohort of 236 cases that presented with a cranial DAVF between June 1984 and May 2001 was reviewed for the consequences of long-term persistent cortical venous reflux (CVR).

Methods

—

A group of 118 cranial DAVFs was selected for the presence of CVR. All patients were offered treatment aimed at the disconnection of the CVR. Patients who declined or had partial treatment with persistence of the CVR had long-term clinical and angiographic follow-up to study the disease course of this select group.

Results

—

Treatment was instituted in 101 of the 118 patients (85.6%). Three patients were lost to follow-up. The remaining 14 nontreated patients (11.9%) and the partially treated patients (n=6) were assessed clinically and angiographically over time. The mean follow-up in this select group was 4.3 years (86.9 patient-years). During follow-up, 7 patients suffered an intracranial hemorrhage (35%). The incidence of nonhemorrhagic neurological deficit was 30%. Nine patients (45%) died: 6 patients expired after a hemorrhage, and 3 patients died of progressive neurological deterioration. Two patients demonstrated a spontaneous closure of the DAVF (10%).

Conclusions

—

Persistence of the CVR in cranial DAVFs yields an annual mortality rate of 10.4%. Excluding events at presentation, in this series the annual risk for hemorrhage or nonhemorrhagic neurological deficit during follow-up was 8.1% and 6.9%, respectively, resulting in an annual event rate of 15.0%.
Association Between Carotid Intima-Media Thickness and Low-Density Lipoprotein Size and Susceptibility of Low-Density Lipoprotein to Oxidation in Asymptomatic Members of Familial Combined Hyperlipidemia Families
Authors: Liu Ming-Lin , Ylitalo Kati , Nuotio Ilpo , Salonen Riitta , Salonen Jukka T. , Taskinen Marja-Riitta
Published: July 2002

Background and Purpose

—

In addition to low-density lipoprotein (LDL) cholesterol, small, dense LDL particles and oxidative modification of LDL have been linked to the pathogenesis of atherosclerosis. The present study was aimed at investigating the association between carotid artery intima-media thickness (IMT) and LDL particle size and susceptibility of LDL to oxidation in vitro in asymptomatic members of familial combined hyperlipidemia (FCHL) families.

Methods

—

LDL particle size, susceptibility of LDL to oxidation in vitro, and carotid IMT were measured in 148 asymptomatic FCHL family members.

Results

—

LDL particle size and lag time for LDL oxidation were reduced in hyperlipidemic compared with normolipidemic family members. LDL particle size, serum total cholesterol, and α-tocopherol in LDL were independently associated with lag time for LDL oxidation in multivariate analysis. LDL particle size was associated with carotid mean IMT independently of clinical, lipid, and antioxidant variables in multivariate analysis. Although the susceptibility of LDL to oxidation in vitro was correlated with mean IMT, it did not have a significant independent contribution to variation in mean IMT in the multivariate model.

Conclusions

—

We conclude that LDL particle size but not susceptibility of LDL to oxidation in vitro is independently associated with carotid IMT in asymptomatic FCHL family members. These results imply that small, dense LDL as an inherent feature of FCHL is an important diagnostic indicator for coronary artery disease risk in FCHL.
Malignant Infarction in Cats After Prolonged Middle Cerebral Artery Occlusion
Authors: Toyota Shingo , Graf Rudolf , Valentino Mario , Yoshimine Toshiki , Heiss Wolf-Dieter
Published: July 2002

Background and Purpose

—

To study the putative role and predictive significance of glutamate elevation in space-occupying ischemic stroke, we investigated the correlation between perfusional disturbances and glutamate alterations in a transient ischemia model in cats that is susceptible to secondary deterioration after reperfusion.

Methods

—

In 10 halothane-anesthetized cats, the left middle cerebral artery was occluded for 3 hours, followed by 6 hours of reperfusion. Laser-Doppler flowmetry (LDF) probes, microdialysis/high-performance liquid chromatography, and pressure sensors measured simultaneously regional cerebral blood flow (CBF), extracellular amino acids, mean arterial blood pressure, and intracranial pressure, respectively. Cerebral perfusion pressure (CPP) was calculated. In complementary experiments (n=2), regional CBF was assessed by sequential positron emission tomography.

Results

—

Middle cerebral artery occlusion reduced LDF-measured CBF in all animals to <25% of control. In 5 of 10 cats, glutamate rose approximately 30-fold during ischemia. LDF-measured CBF and glutamate primarily recovered after reperfusion. Glutamate rose again in the late reperfusion phase, when CPP decreased to <60 mm Hg, and symptoms of transtentorial herniation were recognized. Positron emission tomography revealed ischemic thresholds of 15 to 20 mL/100 g per minute for secondary deterioration. In the other 5 cats, ischemic elevation of glutamate was significantly smaller, and signs of secondary deterioration were not recognized.

Conclusions

—

Glutamate determinations during ischemia predict fatal outcome, as do intracranial pressure and CPP measurements during early reperfusion. Secondary amino acid elevation during reperfusion is presumably caused by a drastic decrease of CPP to <50 mm Hg in the final stage of space-occupying, malignant focal ischemia. At this stage, a further progression of injury due to increased glutamate may be irrelevant with respect to fatal outcome.
Modified National Institutes of Health Stroke Scale for Use in Stroke Clinical Trials
Authors: Meyer Brett C. , Hemmen Thomas M. , Jackson Christy M. , Lyden Patrick D.
Published: July 2002

Background and Purpose

—

To prospectively evaluate the reliability and validity of this previously developed stroke scale in an independently collected cohort. The National Institutes of Health Stroke Scale (NIHSS) has been criticized for its complexity and variability. Prior formal clinimetric analyses were used to obtain a modified version of NIHSS (mNIHSS), which retrospectively demonstrated improved reliability and validity. We sought to prospectively measure the reliability and validity of the mNIHSS.

Methods

—

Forty-five patients with a history of stroke or intracerebral hemorrhage were evaluated at the University of California, San Diego, Stroke Center from September 2000 through March 2001. Each patient was tested by 2 NIHSS-certified neurologists using the NIHSS, mNIHSS, Barthel Index, and Modified Rankin scales.

Results

—

There were a large percentage of high κ values using the mNIHSS. Only 10 (66.67%) of 15 NIHSS κ scores showed excellent agreement, whereas 10 (90.91%) of 11 mNIHSS κ scores showed excellent agreement. As predicted, the mNIHSS was more reliable than the NIHSS because of the exclusion of items with low κ values. With the use of correlation coefficient analysis, the mNIHSS was as valid as the NIHSS.

Conclusions

—

This prospective study found high reliability and continued validity by using a previously developed mNIHSS. Items found to have low κ values were consistent with the previously derived retrospective mNIHSS. The resulting mNIHSS scale has much higher κ values. The mNIHSS showed improved agreement between examiners and was also easier to administer, having fewer and simpler items. Further prospective evaluation should assess whether the mNIHSS could be used in lieu of the NIHSS.
Inflammation, Hemostatic Markers, and Antithrombotic Agents in Relation to Long-Term Risk of New Cardiovascular Events in First-Ever Ischemic Stroke Patients
Authors: Di Napoli Mario , Papa Francesca
Published: July 2002

Background and Purpose

—

The measurement of markers of inflammation or thrombosis has been proposed as a method to improve the prediction of risk in patients with vascular disease. We evaluated the usefulness of these markers as predictors of cardiovascular events in ischemic stroke patients.

Methods

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We analyzed levels of C-reactive protein (CRP), fibrinogen, and D-dimer within the first 24 hours after stroke onset in 473 first-ever ischemic stroke patients and determined the cumulative survival curves free of cardiovascular events in relation to the level of each of these markers according to the Kaplan-Meier method. We adjusted for possible confounding variables using a multivariate Cox proportional-hazards model.

Results

—

Patients in the highest tertiles of D-dimer, fibrinogen, and CRP were associated with an excess risk of new cardiovascular events of 36% (
P
=0.0134), 63% (
P
<0.0001), and 72% (
P
<0.0001), respectively, compared with patients in the lowest tertile. The patients in the highest tertile of CRP had 4 times the risk (hazard ratio, 4.04;
P
<0.0001) of a new cardiovascular event. Smoking, age, sex, and body mass index did not modify risk, and risk was independent of other confounding variables and of D-dimer and fibrinogen levels. The use of ticlopidine was associated with a significant risk reduction among patients with lower (86%,
P
=0.0159) and middle (69%,
P
<0.0001) levels of CRP, whereas a nonsignificant excess risk (27%,
P
=0.3896) was evident among those with the highest levels.

Conclusions

—

Elevated levels of CRP, more than of D-dimer and fibrinogen, are related to the risk of new cardiovascular events after ischemic stroke. The efficacy of antiplatelet therapy in secondary prevention appears to be directly related to level of inflammatory and thrombotic markers.
Carotid Plaque Ultrasonic Heterogeneity and Severity of Stenosis
Authors: AbuRahma Ali F. , Wulu John T. , Crotty Brad
Published: July 2002

Background and Purpose

—

Several studies have reported on the correlation of ultrasonic carotid plaque morphology, cerebrovascular symptoms, and intraplaque hemorrhage. This study correlates ultrasonic carotid plaque morphology with the degree of carotid stenosis.

Methods

—

Carotid arteries (n=2460) were examined by using color duplex ultrasound during a 1-year period. Carotid stenoses were classified into <50%, 50% to <60%, 60% to <70%, and >70% to 99%. Ultrasonic plaque morphology was characterized as either heterogeneous (mixed hyperechoic, hypoechoic, and isoechoic) or homogeneous.

Results

—

Heterogeneous plaques were noted in 138 of 794 arteries with <50% stenosis, in 191 of 564 arteries with 50% to <60% stenosis, in 301 of 487 arteries with 60% to <70% stenosis, and in 496 of 615 arteries with 70% to 99% stenosis. The higher the degree of stenosis, the more likely it is to be associated with heterogeneous plaques. Heterogeneous plaques were present in 59% of the arteries with ≥50% stenoses versus 17% of the arteries with <50% stenoses, in 72% of the arteries with ≥60% stenoses versus 24% of the arteries with <60% stenosis, and in 80% of the arteries with ≥70% stenoses versus 34% of the arteries with <70% stenoses (
P
<0.0001 and odds ratios of 6.9, 8.1, and 8.0, respectively). Heterogeneous plaques were associated with an incidence of symptoms that was higher than that for homogeneous plaques for all grades of stenoses; percentages were, respectively, as follows: 68% versus 16% for <50% stenosis; 76% versus 21% for 50% to <60% stenosis; 79% versus 23% for 60% to <70% stenosis, and 86% versus 31% for ≥70% to 99% stenosis (
P
<0.0001 and odds ratios of 8.9, 11.9, 12.6, and 13.7, respectively). Heterogeneity of plaques was more positively correlated with symptoms than with any degree of stenosis (regardless of plaque structure). Eighty percent of all heterogeneous plaques were symptomatic versus 58% for all stenoses ≥50%, 68% for all stenoses ≥60%, and 75% for all stenoses ≥70% (
P
<0.0001,
P
<0.0001, and
P
=0.02, respectively).

Conclusions

—

The higher the degree of carotid stenosis, the more likely it is to be associated with ultrasonic heterogeneous plaque and cerebrovascular symptoms. Heterogeneity of the plaque was more positively correlated with symptoms than with any degree of stenosis. These findings suggest that plaque heterogeneity should be considered in selecting patients for carotid endarterectomy.