bluuebunny/crossref_metadata_2025 huggingface dataset:
Hypertrophic Cardiomyopathy in Cardiac Myosin Binding Protein-C Knockout Mice
Authors: Harris Samantha P. , Bartley Christopher R. , Hacker Timothy A. , McDonald Kerry S. , Douglas Pamela S. , Greaser Marion L. , Powers Patricia A. , Moss Richard L.
Published: July 2002

Familial hypertrophic cardiomyopathy (FHC) is an inherited autosomal dominant disease caused by mutations in sarcomeric proteins. Among these, mutations that affect myosin binding protein-C (MyBP-C), an abundant component of the thick filaments, account for 20% to 30% of all mutations linked to FHC. However, the mechanisms by which MyBP-C mutations cause disease and the function of MyBP-C are not well understood. Therefore, to assess deficits due to elimination of MyBP-C, we used gene targeting to produce a knockout mouse that lacks MyBP-C in the heart. Knockout mice were produced by deletion of exons 3 to 10 from the endogenous cardiac (c) MyBP-C gene in murine embryonic stem (ES) cells and subsequent breeding of chimeric founder mice to obtain mice heterozygous (+/−) and homozygous (−/−) for the knockout allele. Wild-type (+/+), cMyBP-C
+/−
, and cMyBP-C
−/−
mice were born in accordance with Mendelian inheritance ratios, survived into adulthood, and were fertile. Western blot analyses confirmed that cMyBP-C was absent in hearts of homozygous knockout mice. Whereas cMyBP-C
+/−
mice were indistinguishable from wild-type littermates, cMyBP-C
−/−
mice exhibited significant cardiac hypertrophy. Cardiac function, assessed using 2-dimensionally guided M-mode echocardiography, showed significantly depressed indices of diastolic and systolic function only in cMyBP-C
−/−
mice. Ca
2+
sensitivity of tension, measured in single skinned myocytes, was reduced in cMyBP-C
−/−
but not cMyBP-C
+/−
mice. These results establish that cMyBP-C is not essential for cardiac development but that the absence of cMyBP-C results in profound cardiac hypertrophy and impaired contractile function.
Identification of IEX-1 as a Biomechanically Controlled Nuclear Factor-κB Target Gene That Inhibits Cardiomyocyte Hypertrophy
Authors: De Keulenaer Gilles W. , Wang Yanlin , Feng Yajun , Muangman Suphi , Yamamoto Keiji , Thompson John F. , Turi Thomas G. , Landschutz Katherine , Lee Richard T.
Published: July 2002

Abstract—

Biomechanical strain is a stimulus for cardiomyocyte hypertrophy and heart failure, but the underlying molecular mechanisms remain incompletely understood. Using an in vivo murine model of pressure overload and an in vitro model of mechanical stimulation of primary cardiomyocytes, we identified
iex-1
as a gene activated during the early response of cardiomyocytes to hypertrophic stimuli and as a gene product that inhibits hypertrophy without affecting cardiomyocyte viability. On stimulation of cardiomyocytes,
iex-1
mRNA and protein expression increased and translocation of the gene product to the cardiomyocyte nucleus occurred.
iex-1
has previously been proposed as a mediator of NF-κB-dependent cell survival and growth in tumor cells. Here, we demonstrate that the biomechanical induction of
iex-1
in cardiomyocytes was NF-κB-dependent, as overexpression of the NF-κB inhibitor IκBα completely inhibited strain-mediated
iex-1
mRNA accumulation. The functional role of
iex-1
was investigated by overexpressing wild-type
iex-1
with replication-defective adenoviral gene transfer. Overexpression of
iex-1
abolished cardiomyocyte hypertrophy by mechanical strain, phenylephrine, or endothelin-1 at levels that did not affect cell viability. These studies identify
iex-1
as a biomechanical stress-inducible and NF-κB-dependent gene in cardiac muscle cells during the acute phase of hypertrophy with negative growth regulatory effects that may counterbalance early hypertrophic responses in activated cardiomyocytes.
Role of α
4
Integrin and VCAM-1 in CD18-Independent Neutrophil Migration Across Mouse Cardiac Endothelium
Authors: Bowden Robert A. , Ding Zhi-Ming , Donnachie Elizabeth M. , Petersen Thomas K. , Michael Lloyd H. , Ballantyne Christie M. , Burns Alan R.
Published: July 2002

Myocardial damage due to reperfusion of ischemic tissue is caused primarily by infiltrating neutrophils. Although leukocyte β
2
integrins (CD18) play a critical role, significant neutrophil emigration persists when CD18 is neutralized or absent. This study examined the role of leukocyte β
1
integrin (α
4
) and its endothelial ligand VCAM-1 in CD18-independent neutrophil migration across cardiac endothelium. In a mouse model of myocardial ischemia and reperfusion, we show that compared with wild-type mice, neutrophil infiltration efficiency was reduced by 50% in CD18-null mice; in both types of mice, myocardial VCAM-1 staining increased after reperfusion. In wild-type mice, antibodies against CD18, ICAM-1 (an endothelial ligand for CD18), or VCAM-1 given 30 minutes before ischemia did not block neutrophil emigration at 3 hours reperfusion. Although anti-VCAM-1 attenuated neutrophil emigration by 90% in CD18-null mice, it did not diminish myocardial injury. To determine if CD18-independent neutrophil emigration was a tissue-specific response, we used isolated peripheral blood neutrophils from wild-type or CD18-null mice and showed neutrophil migration across lipopolysaccharide-activated cultured cardiac endothelium is CD18-independent, whereas migration across endothelium obtained from inferior vena cava is CD18-dependent. Consistent with our in vivo findings, migration of CD18-deficient neutrophils on cardiac endothelial monolayers is blocked by antibodies against α
4
integrin or VCAM-1. We conclude tissue-specific differences in endothelial cells account, at least partially, for CD18-independent neutrophil infiltration in the heart.
Regulation of Endothelial Matrix Metalloproteinase-2 by Hypoxia/Reoxygenation
Authors: Ben-Yosef Yaara , Lahat Nitza , Shapiro Sarah , Bitterman Haim , Miller Ariel
Published: July 2002

Among the consequences resulting from the exposure of endothelial cells (ECs) to ischemia/reperfusion is angiogenesis, involving degradation of vascular basement membrane and extracellular matrix. Matrix metalloproteinase (MMP)-2, a member of the MMP family, partakes in this process. MMP-2, secreted as a proenzyme, undergoes activation through interaction with membrane type (MT)1-MMP and the endogenous tissue inhibitor of MMPs (TIMP)-2. Although hypoxia and reoxygenation (H/R) are major constituents of ischemia/reperfusion processes, their direct effects on endothelial MMP-2 have been scarcely investigated. This study examined the in vitro effects of H/R on human macrovascular ECs (EAhy 926). The level of MMP-2 mRNA (Northern blot) and protein (zymography, ELISA) and the mRNA of its activator (MT1-MMP) and inhibitor (TIMP-2) were analyzed. Short (6-hour) hypoxia inhibited the mRNA expression of MMP-2, MT1-MMP, and TIMP-2, culminating in reduced latent and active MMP-2 protein. Prolonged (24-hour) hypoxia further suppressed MT1-MMP and TIMP-2 mRNA, whereas it enhanced MMP-2 mRNA and enzyme secretion (after 48-hour hypoxia). Reoxygenation did not influence the inhibited TIMP-2 but upregulated MMP-2 and MT1-MMP mRNA expression, leading to enhanced secretion of active MMP-2 protein. These results demonstrate H/R-mediated modulation of EC MMP-2 at both transcriptional and posttranscriptional levels. Prolonged hypoxia of ECs appears to enhance MMP-2 production and secretion, whereas reoxygenation further increases its level. These H/R-mediated effects on MMPs have the potential of enabling EC migration and possible angiogenesis.
Histone Acetylation and Recruitment of Serum Responsive Factor and CREB-Binding Protein Onto SM22 Promoter During SM22 Gene Expression
Authors: Qiu Ping , Li Li
Published: July 2002

Chromatin acetylation and deacetylation catalyzed by histone acetyltransferases (HATs) and histone deacetylases (HDACs) are closely related to eukaryotic gene transcription. Although the binding of serum response factor (SRF) to the CArG boxes in the promoter region is necessary for SM22 expression, it has never been examined whether the local chromatin modification is involved in SM22 gene regulation. In this study, we used the SM22 gene as a model to address whether transcriptional activation of the gene can be manipulated through adjusting histone acetylation of the chromatin template and whether SRF- and HAT-containing coactivators can be recruited onto the SM22 promoter region during gene activation. Here, we showed that the stimulation of the SM22 promoter by the coactivator CREB-binding protein (CBP) was dependent on HAT activity. Overexpression of HDACs decreased SM22 promoter activity, whereas trichostatin A, an HDAC inhibitor, stimulated SM22 promoter activity in a CArG box-dependent manner and induced endogenous SM22 gene expression. Chromatin immunoprecipitation assays showed that trichostatin A treatment in 10T1/2 cells induces chromatin hyperacetylation in the SM22 gene. Although histone hyperacetylation of the SM22 gene occurred during SM22 gene expression and SRF and CBP immunocomplexes possess HAT activities in smooth muscle cells, both SRF and CBP were recruited to the CArG box-containing region of the promoter. This study provides evidence that chromatin acetylation is involved in smooth muscle cell-specific gene regulation.
Domain Mapping Studies Reveal That the M Domain of hsp90 Serves as a Molecular Scaffold to Regulate Akt-Dependent Phosphorylation of Endothelial Nitric Oxide Synthase and NO Release
Authors: Fontana Jason , Fulton David , Chen Yan , Fairchild Todd A. , McCabe Timothy J. , Fujita Naoya , Tsuruo Takashi , Sessa William C.
Published: July 2002

Protein-protein interactions with the molecular chaperone hsp90 and phosphorylation on serine 1179 by the protein kinase Akt leads to activation of endothelial nitric oxide synthase. However, the interplay between these protein-protein interactions remains to be established. In the present study, we show that vascular endothelial growth factor stimulates the coordinated association of hsp90, Akt, and resultant phosphorylation of eNOS. Characterization of the domains of hsp90 required to bind eNOS, using yeast 2-hybrid, cell-based coprecipitation experiments, and GST-fusion proteins, revealed that the M region of hsp90 interacts with the amino terminus of eNOS and Akt. The addition of purified hsp90 to in vitro kinase assays facilitates Akt-driven phosphorylation of recombinant eNOS protein, but not a short peptide encoding the Akt phosphorylation site, suggesting that hsp90 may function as a scaffold for eNOS and Akt. In vivo, coexpression of adenoviral or the cDNA for hsp90 with eNOS promotes nitric oxide release; an effect eliminated using a catalytically functional phosphorylation mutant of eNOS. These results demonstrate that stimulation of endothelial cells with vascular endothelial growth factor recruits eNOS and Akt to an adjacent region on the same domain of hsp90, thereby facilitating eNOS phosphorylation and enzyme activation.
Inhibition of Vascular Smooth Muscle Cell Migration by Cytochrome P450 Epoxygenase-Derived Eicosanoids
Authors: Sun Jianxin , Sui XinXin , Bradbury J. Alyce , Zeldin Darryl C. , Conte Michael S. , Liao James K.
Published: July 2002

Vascular smooth muscle cell (SMC) migration and proliferation contribute to neointimal hyperplasia and restenosis after vascular injury. The epoxyeicosatrienoic acids (EETs), which are products of cytochrome P450 (CYP) epoxygenases, possess vasodilatory, antiinflammatory, and fibrinolytic properties. To determine whether these compounds also possess antimigratory and antiproliferative properties, we stimulated rat aortic SMCs with either 20% serum or platelet-derived growth factor (PDGF-BB, 20 ng/mL). In a concentration-dependent manner, treatment with EETs, particularly 11,12-EET, inhibited SMC migration through a modified transwell filter by 53% to 60%. EETs, however, have no inhibitory effects on PDGF-stimulated SMC proliferation. Adenoviral-mediated overexpression of the CYP isoform, CYP2J2, in SMCs also inhibited serum- and PDGF-induced SMC migration by 32% and 26%, respectively; both effects of which were reversed by the CYP inhibitors SKF525A or clotrimazole, but not by the K
Ca
channel blocker, charybdotoxin, or the cyclooxygenase inhibitor, diclofenac. The effect of EETs correlated with increases in intracellular cAMP levels. Indeed, forskolin and 8-bromo-cAMP exert similar inhibitory effects on SMC migration as 11,12-EET and the effects of 11,12-EET were blocked by cAMP and protein kinase A (PKA) inhibitors. These findings indicate that EETs possess antimigratory effects on SMCs through the cAMP-PKA pathway and suggest that CYP epoxygenase-derived eicosanoids may play important roles in vascular disease and remodeling.
Recombinant Apolipoprotein A-I
Milano
Infusion Into Rabbit Carotid Artery Rapidly Removes Lipid From Fatty Streaks
Authors: Chiesa Giulia , Monteggia Elena , Marchesi Marta , Lorenzon Paolo , Laucello Massimo , Lorusso Vito , Di Mario Carlo , Karvouni Evangelia , Newton Roger S. , Bisgaier Charles L. , Franceschini Guido , Sirtori Cesare R.
Published: July 2002

Apolipoprotein A-I
Milano
(AIM), a natural variant of human apolipoprotein A-I, confers to carriers a significant protection against vascular disease. In previous studies, administration of recombinant AIM-phospholipid (AIM-PL) complexes to hypercholesterolemic rabbits markedly inhibited neointimal formation after arterial injury; moreover, repeated injections of AIM-PL in apoE-deficient mice significantly reduced atherosclerosis progression. The objective of the present study was to determine if a single localized infusion of AIM-PL complexes administered directly to atheromatous lesions could promote plaque regression. Lipid-rich, atheromatous plaques were generated at both common carotid arteries of 25 rabbits by applying a perivascular electric injury, followed by 1.5% cholesterol diet for 90 days. Rabbits were infused with either saline, phospholipid vesicles, or 3 different AIM-PL doses (250, 500, or 1000 mg of protein) delivered through an intravascular ultrasound (IVUS) catheter positioned at the origin of the right carotid. The lesions at the left carotid artery were therefore exposed to the agents systemically. Infusion of AIM-PL at the 2 highest doses caused reduction of right carotid artery plaque area by the end a 90-minute infusion as assessed by IVUS analysis. Plaque area regression was confirmed by histology in carotid arteries receiving direct (500 and 1000 mg doses) and systemic (500 mg dose) delivery, 72 hours after the start of the treatment. Plaque lipid content was associated with significant and similar decreases in Oil Red O staining in both arteries. These results suggest AIM-PL complexes enhanced lipid removal from arteries is the mechanism responsible for the observed plaque changes.
Cholinergic Atrial Fibrillation in a Computer Model of a Two-Dimensional Sheet of Canine Atrial Cells With Realistic Ionic Properties
Authors: Kneller James , Zou Renqiang , Vigmond Edward J. , Wang Zhiguo , Leon L. Joshua , Nattel Stanley
Published: July 2002

Classical concepts of atrial fibrillation (AF) have been rooted in Moe’s multiple-wavelet hypothesis and simple cellular-automaton computer model. Recent experimental work has raised questions about the multiple-wavelet mechanism, suggesting a discrete “driver region” underlying AF. We reexplored the theoretical basis for AF with a 2-dimensional computer model of a 5×10-cm sheet of atrial cells with realistic ionic and coupling properties. Vagal actions were formulated based on patch-clamp studies of acetylcholine (ACh) effects. In control, a single extrastimulus resulted in a highly meandering unstable spiral wave. Simulated electrograms showed fibrillatory activity, with a dominant frequency (DF, 6.5 Hz) that correlated with the mean rate. Uniform ACh reduced core meander of the spiral wave by ≈70% (as measured by the standard deviation of spiral-wave tip position) and accelerated the DF to 17.0 Hz. Simulated vagally induced refractoriness heterogeneity caused wavefront breakup as accelerated reentrant activity in regions of short refractoriness impinged on regions unable to respond in a 1:1 fashion because of longer refractoriness. In 7 simulations spanning the range of conditions giving sustained AF, 5 were maintained by single dominant spiral waves. On average, 3.0±1.3 wavelets were present (range, 1 to 7). Most wavelets were short-lived and did not contribute to AF maintenance. In contrast to predictions of the multiple-wavelet hypothesis, but in agreement with recent experimental evidence, our model indicates that AF can result from relatively stable primary spiral-wave generators and is significantly organized. Our results suggest that vagal AF may arise from ACh-induced stabilization of the primary spiral-wave generator and disorganization of the heterogeneous tissue response. The full text of this article is available at http://www.circresaha.org.
Osteopontin Plays an Important Role in the Development of Medial Thickening and Neointimal Formation
Authors: Isoda Kikuo , Nishikawa Kenichirou , Kamezawa Yashuhiro , Yoshida Mikoto , Kusuhara Masatoshi , Moroi Masao , Tada Norihiro , Ohsuzu Fumitaka
Published: July 2002

Osteopontin (OPN) is a soluble secreted phosphoprotein that binds with high affinity to several integrins and it has been found at the site of atherosclerotic lesions. However, the role of OPN expression in vivo is still poorly understood. To investigate the physiological role of OPN in detail, we generated transgenic mice (Tg) overexpressing the OPN gene under control of the cytomegalovirus enhancer/chicken β-actin promoter. We detected OPN mRNAs in almost all tissues of 3 lines of Tg mice by Northern blotting. The serum levels of OPN were significantly higher in Tg than in non-Tg mice (782±107 versus 182±44 ng/mL;
P
<0.001). Compared with non-Tg mice, a 73% (88±6 versus 51±7 μm;
P
<0.001) and 94% (126±15 versus 73±11 μm;
P
<0.0001) increase in the medial thickness of the aorta was determined in Tg mice at 16 and 32 weeks after birth. However, we found no evidence of inflammatory cells adhering to endothelial cells, intimal hyperplasia, or calcification in any region of Tg mice without artery injury. We then investigated the effect of cuff-induced injury to the femoral artery. The intimal thickening in Tg mice increased 2.9-fold more than that in non-Tg mice (4.9±1.9 versus 1.7±0.4 μm;
P
=0.022). The expression of OPN induces both medial thickening without injury and neointimal formation after injury, thus suggesting that OPN plays a role in the development of atherosclerosis, vascular remodeling, and restenosis after angioplasty in vivo.
No Association of Paraoxonase Genotype or Atherosclerosis With Cerebral Amyloid Angiopathy
Authors: Yamada M. , Sodeyama N. , Itoh Y. , Otomo E. , Matsushita M. , Mizusawa H.
Published: July 2002

Background and Purpose

—

Both cerebral amyloid angiopathy (CAA) and paraoxonase have been reported to be related to lipid metabolism and atherosclerosis. We investigated whether the paraoxonase gene (
PON1
) polymorphism and atherosclerosis are associated with risk of CAA.

Methods

—

Associations of the
PON1
polymorphism and atherosclerosis of the aorta and coronary and cerebral arteries with the severity of CAA were investigated in 154 elderly Japanese individuals, including 47 patients with Alzheimer’s disease.

Results

—

The
PON1
polymorphism or severity of atherosclerosis of the arteries was not associated with the severity of CAA.

Conclusions

—

The
PON1
polymorphism and atherosclerosis would not appear to be associated with risk of CAA in the elderly, although further study with larger samples is necessary for confirmation.
Platelet P-Selectin Levels in Relation to Plasma Soluble P-Selectin and β-Thromboglobulin Levels in Atrial Fibrillation
Authors: Kamath Sridhar , Blann Andrew D. , Caine Graham J. , Gurney David , Chin Bernard S.P. , Lip Gregory Y.H.
Published: July 2002

Background and Purpose

—

The increased risk of stroke and thromboembolism in atrial fibrillation (AF) may be related to a prothrombotic or hypercoagulable state, with abnormalities of hemostasis and platelet activation. To investigate the role of platelets in AF and the influence of antithrombotic therapy, we developed and then applied a new assay to detect the absolute amount of P-selectin per platelet (pP-selectin) based on cell lysis. Thus, pP-selectin in AF patients was compared with that of healthy controls and also with plasma soluble P-selectin (sP-selectin) and β-thromboglobulin as established indices of platelet activation.

Methods

mdash;

We studied 122 patients (mean [SD] age, 71 [9] years; 65 men) with chronic AF of >6 weeks’ duration: 34 were not on antithrombotic therapy, 30 were taking aspirin (75 to 300 mg/d), and 58 were fully anticoagulated with warfarin. pP-selectin was compared with sP-selectin and plasma β-thromboglobulin levels (enzyme-linked immunosorbent assay). Results were compared with those of 23 healthy controls (mean [SD] age, 74 [9] years; 7 men) in sinus rhythm.

Results

—

pP-selectin was significantly lower in AF patients on no antithrombotic therapy (
P
∓0.03) than in healthy controls, but sP-selectin and β-thromboglobulin levels were not significantly different and did not differ in patients taking aspirin or warfarin. However, pP-selectin was lower in patients with AF on aspirin than in those on warfarin (
P
<0.05). pP-selectin/sP-selectin correlated significantly in healthy controls (
r
∓0.47,
P
∓0.03) but inversely (
r
∓−0.43,
P
∓0.03) in AF patients on no antithrombotic therapy.

Conclusions

—

Lower levels of pP-selectin may represent a depletion of pP-selectin after platelet activation in AF. Aspirin further decreases pP-selectin levels compared with warfarin. On the basis of the principle of platelet lysis, we demonstrate that it is possible to determine the amount of P-selectin per platelet, which may be regulated in the megakaryocyte through a cyclooxygenase-dependent pathway.
Retinal and Optic Nerve Degeneration After Chronic Carotid Ligation
Authors: Stevens W. Dale , Fortin Teresa , Pappas Bruce A.
Published: July 2002

Background and Purpose

—

Carotid artery disease can cause chronic retinal ischemia, resulting in transient or permanent blindness, pupillary reflex dysfunction, and retinal degeneration. This experiment investigated the effects of chronic retinal ischemia in an animal model involving permanent carotid occlusion. The time course of retinal pathology and the role of light in this pathology were examined.

Methods

—

Sprague-Dawley rats underwent permanent bilateral occlusion of the common carotid arteries or sham surgery. Half of the animals were postsurgically housed in darkness, and half were housed in a 12-hour light/dark cycle. Animals were killed at 3, 15, and 90 days after surgery. Stereological techniques were used to count the cells of the retinal ganglion cell layer. Thy-1 immunoreactivity was assessed to specifically quantify loss of retinal ganglion cells. The thicknesses of the remaining retinal sublayers were measured. Optic nerve degeneration was quantified with the Gallyas silver staining technique.

Results

—

Permanent bilateral occlusion of the common carotid arteries resulted in loss of the pupillary reflex to light in 58% of rats. Eyes that lost the reflex showed (1) optic nerve degeneration at 3, 15, and 90 days after surgery; (2) a reduction of retinal ganglion cell layer neurons and Thy-1 immunoreactivity by 15 and 90 days; and (3) a severe loss of photoreceptors by 90 days when postsurgically housed in the light condition only.

Conclusions

—

Ischemic damage to the optic nerve caused loss of pupillary reflex and death of retinal ganglion cells in a subset of rats. Subsequently, light toxicity induced death of the photoreceptors.
Ischemia and Ischemic Tolerance Induction Differentially Regulate Protein Expression of GluR1, GluR2, and AMPA Receptor Binding Protein in the Gerbil Hippocampus
Authors: Sommer Clemens , Kiessling Marika
Published: July 2002

Background and Purpose

—

Postischemic delayed neuronal death (DND) of hippocampal CA1 neurons has been suggested to occur as a result of formation of calcium-permeable α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors lacking the GluR2 subunit (GluR2 hypothesis). DND can be prevented by a short tolerance-inducing ischemic period. The present study was designed to assess whether postischemic protein levels of GluR2 predict neuronal death. Additionally, the role of AMPA receptor binding protein (ABP) was investigated with respect to neuronal death or survival.

Methods

—

Postischemic protein expression of GluR1, GluR2, and ABP was analyzed in 3 experimental paradigms of transient global ischemia with the use of subunit-specific antisera and semiquantitative densitometric evaluation. Gerbils were subjected (1) to a 5-minute ischemic period resulting in DND of CA1 neurons; (2) to a 2.5-minute period of ischemia mediating tolerance induction; and (3) to 5 minutes of ischemia in the ischemia-tolerant state (2.5+5 minutes of ischemia 4 days apart).

Results

—

The major finding was that GluR2 protein levels were significantly downregulated in neuronal subpopulations destined to survive, ie, in CA1 principal neurons after ischemic tolerance induction and in the ischemia-tolerant state, as well as in CA3 neurons after a 5-minute period of ischemia. ABP expression remained unaffected.

Conclusions

—

Our results modify the GluR2 hypothesis in that postischemic GluR2 reduction also occurs in hippocampal CA1 and CA3 principal neurons without subsequent neuronal death. ABP is obviously not involved in mechanisms of DND or ischemic tolerance induction.
Quantification of Perfusion Using Bolus Tracking Magnetic Resonance Imaging in Stroke
Authors: Calamante F. , Gadian D.G. , Connelly A.
Published: July 2002

Background

—

MR techniques have been very powerful in providing indicators of tissue perfusion, particularly in studies of cerebral ischemia. There is considerable interest in performing absolute perfusion measurements, with the aim of improving the characterization of tissue “at risk” of stroke. However, some important caveats relating to absolute measurements need to be taken into account. The purpose of this article is to discuss some of the issues involved and the potential implications for absolute cerebral blood flow measurements in clinical use.

Summary of Comment

—

In bolus tracking MRI, deconvolution of the concentration-time course can in theory provide accurate quantification. However, there are several important assumptions in the tracer kinetic model used, some of which may be invalid in cerebral ischemia. These can introduce significant errors in perfusion quantification.

Conclusions

—

Although we believe that bolus tracking MRI is a powerful technique for the evaluation of perfusion in cerebral ischemia, interpretation of perfusion maps requires caution; this is particularly true when absolute quantification is attempted. Work is currently under way in a number of centers to address these problems, and with appropriate modeling they may be overcome in the future. In the interim, we believe that it is necessary for users of bolus tracking perfusion data to be aware of the current technical limitations if they are to avoid misinterpretation or overinterpretation of their findings.
Influence of Apolipoprotein E, Smoking, and Alcohol Intake on Carotid Atherosclerosis
Authors: Djoussé Luc , Myers Richard H. , Province Michael A. , Hunt Steven C. , Eckfeldt John H. , Evans Gregory , Peacock James M. , Ellison R. Curtis
Published: July 2002

Background and Purpose

—

Apolipoprotein E (apoE) isoforms and lifestyle factors play an important role in the development of coronary heart disease. The association of apoE and carotid atherosclerosis remains controversial.

Methods

—

We investigated the relation of apoE, cigarette smoking, alcohol drinking, and their interaction with carotid atherosclerosis on 544 individuals free of coronary heart disease in the National Heart, Lung, and Blood Institute (NHLBI) Family Heart Study. Atherosclerotic lesions of the carotid arteries were detected through high-resolution ultrasound.

Results

—

Subjects in the apoE4 group had lower blood pressure, lower high-density lipoprotein cholesterol, and higher low-density lipoprotein cholesterol. In a multivariate logistic regression model, apoE isoforms and alcohol consumption were not significantly associated with the prevalence odds of carotid atherosclerosis (
P
=0.94 and 0.98, respectively, for trend). In contrast, compared with those who never smoked, the prevalence odds ratios for carotid atherosclerosis were 1.7 [95% confidence interval (CI),1.1 to 2.7], 2.8 (95% CI, 1.2 to 6.2), and 1.9 (95% CI, 0.7 to 5.5) for former smokers, current smokers of 1 to 20 cigarettes per day, and current smokers of >20 cigarettes day, respectively (
P
=0.0018 for trend). We did not find evidence of an interaction between apoE and alcohol consumption. Our data suggested a synergistic effect between the apoE allele ε
4
and smoking on carotid atherosclerosis: odds ratios were 1.7 (95% CI, 0.8 to 3.6) for smoking alone, 1.0 (95% CI, 0.6 to 1.8) for ε
4
alone, and 3.7 (95% CI, 1.1 to 3.6) for the joint presence of the apoE allele ε
4
and smoking.

Conclusions

—

Smoking but not alcohol consumption or ApoE is associated with an increased odds of carotid atherosclerosis. Our data suggest a synergistic effect between the apoE allele ε
4
and smoking on carotid atherosclerosis.
Alzheimer Disease as a Vascular Disorder
Authors: de la Torre J.C.
Published: July 2002

Background

—

The main stumbling block in the clinical management and in the search for a cure of Alzheimer disease (AD) is that the cause of this disorder has remained uncertain until now.

Summary of Review

—

Evidence that sporadic (nongenetic) AD is primarily a vascular rather than a neurodegenerative disorder is reviewed. This conclusion is based on the following evidence: (1) epidemiological studies showing that practically all risk factors for AD reported thus far have a vascular component that reduces cerebral perfusion; (2) risk factor association between AD and vascular dementia (VaD); (3) improvement of cerebral perfusion obtained from most pharmacotherapy used to reduce the symptoms or progression of AD; (4) detection of regional cerebral hypoperfusion with the use of neuroimaging techniques to preclinically identify AD candidates; (5) presence of regional brain microvascular abnormalities before cognitive and neurodegenerative changes; (6) common overlap of clinical AD and VaD cognitive symptoms; (7) similarity of cerebrovascular lesions present in most AD and VaD patients; (8) presence of cerebral hypoperfusion preceding hypometabolism, cognitive decline, and neurodegeneration in AD; and (9) confirmation of the heterogeneous and multifactorial nature of AD, likely resulting from the diverse presence of vascular risk factors or indicators of vascular disease.

Conclusions

—

Since the value of scientific evidence generally revolves around probability and chance, it is concluded that the data presented here pose a powerful argument in support of the proposal that AD should be classified as a vascular disorder. According to elementary statistics, the probability or chance that all these findings are due to an indirect pathological effect or to coincidental circumstances related to the disease process of AD seems highly unlikely. The collective data presented in this review strongly support the concept that sporadic AD is a vascular disorder. It is recommended that current clinical management of patients, treatment targets, research designs, and disease prevention efforts need to be critically reassessed and placed in perspective in light of these important findings.
MRI Evaluation and Functional Assessment of Brain Injury After Hypoxic Ischemia in Neonatal Mice
Authors: Ådén Ulrika , Dahlberg Viktoria , Fredholm Bertil B. , Lai Li-Ju , Chen Zhengguan , Bjelke Börje
Published: July 2002

Background and Purpose

—

Severe perinatal asphyxia is an important cause of brain injury in the newborn infant. We examined early events after hypoxic ischemia (HI) in the 7-day-old mouse brain by MRI and related them to long-term functional effects and histopathology in the same animals at 4 to 5 weeks of age.

Methods

—

HI was induced in 7-day-old CD1 mice by exposure to 8% oxygen for 30 minutes after occlusion of the left common carotid artery. The resulting unilateral focal lesion was evaluated in vivo by MRI (T2 maps and apparent diffusion coefficient maps) at 3, 6, and 24 hours and 5 days after hypoxia. Locomotion and sensorimotor function were analyzed after 3 weeks. Four weeks after HI, the mice were killed, and cresyl violet–stained brain sections were examined morphologically.

Results

—

A decrease in apparent diffusion coefficient values in cortex on the affected side was found at 3 hours after HI. T2 values were significantly increased after 6 hours and remained so for 5 days. Maximal size of the lesion was attained at 3 to 6 hours after HI and declined thereafter. Animals with MRI-detected lesions had decreased forward locomotion, performed worse than controls in the beam-walking test, and showed a unilateral hypotrophy in the cresyl violet–stained brain sections 4 weeks later.

Conclusions

—

The temporal progression of the damage after HI in 7-day-old mice differs from that of the adult brain as judged by MRI. The early lesions detected by MRI were related to functional impairments for these mice in near-adult life.
Prediction of Hemorrhagic Transformation After Thrombolytic Therapy of Clot Embolism
Authors: Neumann-Haefelin C. , Brinker G. , Uhlenküken U. , Pillekamp F. , Hossmann K-A. , Hoehn M.
Published: July 2002

Background and Purpose

—

Thrombolytic treatment of stroke carries the risk of hemorrhagic transformation. Therefore, the potential of MRI for prediction of recombinant tissue plasminogen activator (rtPA)–induced bleeding is explored to identify patients in whom rtPA treatment may provoke such complications.

Methods

—

Spontaneously hypertensive rats (SHR) (n=9) were submitted to middle cerebral artery (MCA) clot embolism, followed 3 hours later by intra-arterial infusion of 10 mg/kg rtPA. Untreated SHR (n=9) were infused with saline. MRI imaging was performed before treatment and included apparent diffusion coefficient (ADC), T2, and perfusion mapping and contrast enhancement with gadolinium-DTPA. The distribution of intracerebral hemorrhages was studied 3 days later by histological staining.

Results

—

Clot embolism led to the rapid decline of ADC in the territory of the occluded artery. Tissue lesion volume derived from ADC imaging increased by 155±69% in the untreated animals and by 168±87% in the treated animals (
P
=NS), determined on the histological sections after 3 days. This same lesion growth in both groups indicated absence of therapeutic effect after 3-hour treatment delay. Hemorrhagic transformations were significantly more frequent in treated SHR (
P
<0.05). In untreated rats, hemorrhages were found in the border zone of the ischemic territory; in treated animals, hemorrhagic transformations occurred in the ischemic core region. rtPA-induced hemorrhages were predicted by a disturbance of the blood-brain barrier in 3 of 4 animals before treatment by Gd-DTPA contrast enhancement but not by ADC, T2, or perfusion imaging. The region of contrast enhancement colocalized with subsequent bleeding in these animals.

Conclusions

—

The disturbance of blood-brain barrier but not of other MR parameters allows risk assessment for hemorrhagic transformation induced by subsequent thrombolytic treatment.
Bone Marrow as a Source of Endothelial Cells and NeuN-Expressing Cells After Stroke
Authors: Hess David C. , Hill William D. , Martin-Studdard Angeline , Carroll James , Brailer Joanna , Carothers Jo
Published: July 2002

Background and Purpose

—

After an ischemic event, bone marrow–derived cells may be involved in reparative processes. There is increasing evidence that bone marrow–derived stem cells may be a source of endothelial cells and organ-specific cells. Our objectives were to determine whether bone marrow–derived cells were a source of endothelial cells and neurons after cerebral ischemia.

Methods

—

We transplanted bone marrow from male C57 BL/6-TgN (ACTbEGFP)1Osb mice, which express green fluorescent protein (GFP), into female C57 BL/6J mice. The recipient mice then underwent suture occlusion of the middle cerebral artery (MCA), and bone marrow– derived cells were tracked by GFP epifluorescence and Y chromosome probe.

Results

—

Within 3 days and at 7 and 14 days after MCA occlusion, bone marrow–derived cells incorporated into the vasculature in the ischemic zone and expressed an endothelial cell phenotype. Few bone marrow–derived cells incorporated into the vasculature 24 hours after MCA occlusion. Some bone marrow–derived cells also expressed the neuronal marker NeuN at 7 and 14 days after ischemia.

Conclusions

—

Postnatal vasculogenesis occurs in the brain in the setting of a cerebral infarction. Bone marrow–derived cells are a source of endothelial cells and NeuN-expressing cells after cerebral infarction. This plasticity may be exploited in the future to enhance recovery after stroke.
Risk of Arterial Thrombosis in Relation to Oral Contraceptives (RATIO) Study
Authors: Kemmeren Jeanet M. , Tanis Bea C. , van den Bosch Maurice A.A.J. , Bollen Edward L.E.M. , Helmerhorst Frans M. , van der Graaf Yolanda , Rosendaal Frits R. , Algra Ale
Published: July 2002

Background and Purpose

—

Epidemiological studies have shown an increased risk of venous thrombosis in women taking third-generation oral contraceptives, ie, those containing the progestogens desogestrel or gestodene. This study assesses the risk of ischemic stroke with several types of oral contraceptives.

Methods

—

A multicenter, population-based, case-control study was performed in 9 Dutch centers in women aged 18 to 49 years. Women with a first ischemic stroke were compared with control women without vascular diseases. The control subjects were recruited by random-digit dialing and were stratified by age, area of residence, and year of stroke. All patients and control subjects filled in a questionnaire about the use of oral contraceptives and risk factors for ischemic stroke. Odds ratios were adjusted for the stratification factors.

Results

—

Two hundred three women with an ischemic stroke and 925 control women were included. The risk of stroke in women using any type of oral contraceptives versus none was 2.3 (95% CI 1.6 to 3.3). Current users of first-generation oral contraceptives had an odds ratio of 1.7 (95% CI 0.7 to 4.4). Low-dose second-generation oral contraceptives increased the risk of stroke 2.4 times (95% CI 1.6 to 3.7), and third-generation oral contraceptives increased the risk of stroke 2.0 times (95% CI 1.2 to 3.5). The risk of stroke in women using third-generation oral contraceptives was not different from that in women using second-generation oral contraceptives (odds ratio 1.0, 95% CI 0.6 to 1.8).

Conclusions

—

Third-generation oral contraceptives (containing desogestrel or gestodene) confer the same risk of first ischemic stroke as second-generation oral contraceptives (containing levonorgestrel).
Color Velocity Imaging Quantification in the Detection of Intracranial Collateral Flow
Authors: Ho S.S.Y. , Metreweli C. , Yu C.H.
Published: July 2002

Background and Purpose

—

The development of intracranial collateral circulation is associated with a lower risk of stroke. A noninvasive technique that can reliably detect the presence of intracranial collaterals would be a valuable factor in the assessment of risk in patients with occlusive cerebrovascular disease.

Methods

—

Color velocity imaging quantification was used to measure the blood flow volume of the common carotid and vertebral arteries in 40 patients with carotid occlusive disease. The blood flow volumes in these arteries were correlated with angiographic evidence of collaterals to establish the best cutoffs for detecting intracranial collateral circulation.

Results

—

A blood flow volume of either ≥370 mL/min in the common carotid artery or ≥120 mL/min in the vertebral artery was indicative of the presence of intracranial collaterals. The sensitivity and specificity for the common carotid artery were 92.3% [95% confidence interval (CI), 62.1 to 99.6] and 92.1% (95% CI, 77.5 to 97.9), respectively. The sensitivity and specificity for the vertebral artery were 75.0% (95% CI, 35.6 to 95.5) and 87.5% (95% CI, 66.5 to 96.7), respectively.

Conclusions

—

Color velocity imaging quantification offers a noninvasive, accurate method for detecting the presence of intracranial collateral circulation and quantifying its magnitude. This technique would be a useful adjunct in screening or continuous monitoring of patients with severe carotid occlusive disease.
Cholesterol Predicts Stroke Mortality in the Women’s Pooling Project
Authors: Horenstein Richard B. , Smith Dean E. , Mosca Lori
Published: July 2002

Background and Purpose

—

Cholesterol is emerging as a risk factor for stroke; however, few data are available regarding the relation of cholesterol and stroke mortality in women and ethnic minorities.

Methods

—

We evaluated the risk of death caused by total stroke, nonhemorrhagic stroke, and hemorrhagic stroke by race, age, and cholesterol quintile in 24 343 women with no previous cardiovascular disease who were participating in 8 US longitudinal, prospective, cohort studies included in the Women’s Pooling Project.

Results

—

We observed 568 stroke deaths (461 nonhemorrhagic, 83 hemorrhagic) for women ≥30 years of age without previous cardiovascular disease during 339 215 person-years of follow-up. In multivariate models, black women <55 years of age had a 76% increased risk of death caused by stroke compared with white women [relative risk (RR), 1.76; 95% confidence interval (CI), 1.10 to 2.81]. For black women <55 years of age, the top compared with the lowest cholesterol quintile (Q5 versus Q1) remained an independent predictor of stroke mortality (RR, 2.58; 95% CI, 1.05 to 6.32) in multivariate models. For white women <55 years of age, Q5 versus Q1 cholesterol did not predict stroke mortality with significance (RR, 1.47; 95% CI, 0.57 to 3.76). In analogous multivariate models, we found a positive relation between continuous cholesterol and nonhemorrhagic stroke death in women <55 years of age (RR, 1.23; 95% CI, 1.02 to 1.49).

Conclusions

—

Our results show that cholesterol is a risk factor for nonhemorrhagic stroke death in women <55 years of age and is more strongly associated with mortality in black women <55 years of age than in white women. These data document the importance of cholesterol in addition to established risk factors for predicting stroke mortality in young women and may guide prevention strategies.
Quantitative and Qualitative Impairments in Skilled Reaching in the Mouse (
Mus musculus
) After a Focal Motor Cortex Stroke
Authors: Farr Tracy D. , Whishaw Ian Q.
Published: July 2002

Background and Purpose

—

Skilled reaching movements are an important aspect of human motor behavior but are impaired after motor system stroke. The purpose of this study was to document skilled movements in mice before and after a focal motor cortex stroke for the purpose of developing a mouse model of human stroke.

Methods

—

Male C57/BL6 mice were trained to reach with a forelimb for food pellets and then given a motor cortex stroke, induced by pial stripping, contralateral to their preferred reaching limb. Reaching success and the movements used in reaching were analyzed by frame-by-frame inspection of presurgical and postsurgical video records.

Results

—

Reaching success was severely impaired after the stroke. Improvement in success over 2 postsurgical weeks was moderate. Analysis of 10 movement components comprising reaches pre- and postsurgically indicated that most of the rotatory movements of the limb used for aiming, advancing, pronating, and supinating the paw were impaired. When successful reaches did occur, body movements that compensated for the impairments in limb rotatory movements aided them.

Conclusions

—

The results indicate that skilled reaching in the mouse is impaired by focal motor cortex stroke and they suggest that the mouse, and the skilled reaching task, provides an excellent model for studying impairments, compensation, and recovery after motor system stroke.
Primary Aortic Valve Replacement With Cryopreserved Aortic Allograft
Authors: Palka Przemysław , Harrocks Susan , Lange Aleksandra , Burstow Darryl J. , O’Brien Mark F.
Published: July 2002

Background
—

Despite the many advantages of an aortic allograft valve (AAV) over a prosthetic aortic valve, its durability is suboptimal. The aims of the present study were to document characteristic features of AAV dysfunction and to investigate factors influencing the development of such dysfunction.

Methods and Results
—

A group of 570 patients (mean age, 48±16 years) with a cryopreserved AAV underwent a follow-up echocardiographic study (mean time after surgery, 6.8 years; range, 1.0 to 22.9 years). Significant AAV regurgitation was present in 14.7% of patients, and AAV stenosis was present in 3.2%. The root replacement subgroup had the smallest number of patients with significant AAV regurgitation (5.0%) compared with the subcoronary (23.0%) or the inclusion cylinder technique subgroup (14.7%). After 10 to 15 years after AAV replacement, grade ≥2 AAV dysfunction was present in 40% of patients in the subcoronary subgroup, but no significant dysfunction was observed in patients in the root replacement subgroup (
P
<0.001). Smaller host aortic annulus size in both subcoronary (coefficient, −0.145;
P
=0.013) and root replacement subgroups (coefficient, −0.249;
P
=0.011) was associated with more frequent AAV dysfunction (grade ≥2). In addition, significant AAV dysfunction was more frequent when patients were younger (coefficient, −0.020;
P
=0.015) in the subcoronary subgroup and the donor was older (coefficient, 0.054;
P
=0.019) in the root replacement subgroup.

Conclusions
—

The present study indicates that the root replacement technique is associated with less frequent AAV degeneration. Our findings should help in establishing more strict selection criteria for surgical replacement procedure type and patient/donor factors for AAV replacement and, therefore, could lead to improve AAV longevity.