bluuebunny/crossref_metadata_2025 huggingface dataset:
Distinction in Genetic Determinants for Injury-Induced Neointimal Hyperplasia and Diet-Induced Atherosclerosis in Inbred Mice
Authors: Kuhel David G. , Zhu Binghua , Witte David P. , Hui David Y.
Published: July 2002

Five inbred strains of mice differing in susceptibility to diet-induced atherosclerosis were compared for neointimal hyperplasia after endothelial denudation with an epoxy resin–modified catheter probe. Results showed that all animals responded similarly to the arterial injury, with increased medial area and thickness after 14 days. In contrast, a significant strain-specific difference in neointimal formation after injury was observed. The atherosclerosis-susceptible C57L/J mice were also susceptible to injury-induced neointimal hyperplasia, and the C3H mice were resistant to both forms of vascular diseases. The 129/Sv mice, which displayed an intermediate level of diet-induced atherosclerosis, also displayed an intermediate level of injury-induced neointimal hyperplasia. Interestingly, the atherosclerosis-susceptible C57BL/6 mice were resistant to neointimal hyperplasia after endothelial denudation, whereas the atherosclerosis-resistant FVB/N mice were susceptible, displaying massive neointimal hyperplasia after arterial injury. All (C57L/J×C57BL/6)F
1
hybrid mice were resistant to injury-induced neointimal hyperplasia. Moreover, N
2
mice generated from backcrossing the F
1
hybrid mice to the susceptible C57L/J mice displayed a range of arterial response to injury, spanning the most severe to the most resistant phenotype. These results indicate that injury-induced neointimal hyperplasia and diet-induced atherosclerosis are controlled by distinct sets of genes; the former appeared to be determined by recessive genes at ≥2 loci.
Interferon-γ–Mediated Downregulation of Cholesterol Efflux and ABC1 Expression Is by the Stat1 Pathway
Authors: Wang Xue-Qing , Panousis Constantinos G. , Alfaro M. Leticia , Evans Glenn F. , Zuckerman Steven H.
Published: July 2002

The pathological role of interferon-γ (IFN-γ) in atherosclerosis is mediated through effects on macrophages, foam cells, and other vascular cells. Recently, we reported that ATP-binding cassette transporter 1(ABC1) message and protein levels were decreased 3- to 4-fold in foam cells by IFN-γ. In the present study, the pathway by which IFN-γ inhibited ABC1 expression was investigated with signal transducers and activators of transcription (Stat1) knockout mice. IFN-γ–stimulated, wild-type, macrophage-derived foam cells, as previously reported, exhibited a decrease in cholesterol efflux and ABC1 expression as well as an increase in acyl coenzyme A:cholesterol-
O
-acyltransferase activity. However, IFN-γ treatment of foam cells from Stat1 knockout mice failed to demonstrate reductions in efflux or ABC1 expression at the message or protein levels, nor were there any increases in acyl coenzyme A:cholesterol-
O
-acyltransferase activity. However, ABC1 mRNA expression in macrophages from Stat1 knockout mice could still be demonstrated to be increased by lipid loading with acetylated low density lipoprotein. Finally, Stat1-independent gene activation by IFN-γ was intact in the Stat1 KO macrophages, inasmuch as IFN-γ was shown to stimulate increases in interleukin-6 production in the Stat1 KO macrophages that were comparable to those observed in the wild-type macrophages. Therefore, Stat1 signaling is necessary and sufficient for the inhibitory effects of IFN-γ on cholesterol efflux and ABC1 expression.
Transforming Growth Factor-β Mediates Balance Between Inflammation and Fibrosis During Plaque Progression
Authors: Lutgens Esther , Gijbels Marion , Smook Marjan , Heeringa Peter , Gotwals Philip , Koteliansky Victor E. , Daemen Mat J.A.P.
Published: July 2002

The transition from stable to rupture-prone and ruptured atherosclerotic plaques involves many processes, including an altered balance between inflammation and fibrosis. An important mediator of both is transforming growth factor (TGF)-β, and a pivotal role for TGF-β in atherogenesis has been postulated. Here, we determine the in vivo effects of TGF-β inhibition on plaque progression and phenotype in atherosclerosis. Recombinant soluble TGF-β receptor II (TGFβRII:Fc), which inhibits TGF-β signaling, was injected in apolipoprotein E-deficient mice for 12 weeks (50 μg, twice a week intraperitoneally) as early treatment (treatment age 5 to 17 weeks) and delayed treatment (age 17 to 29 weeks). In the early treatment group, inhibition of TGF-β signaling treatment resulted in a prominent increase in CD3- and CD45-positive cells in atherosclerotic lesions. Most profound effects were found in the delayed treatment group. Plaque area decreased 37.5% after TGFβRII:Fc treatment. Moreover, plaque morphology changed into an inflammatory phenotype that was low in fibrosis: lipid cores were 64.6% larger, and inflammatory cell content had increased 2.7-fold. The amount of fibrosis decreased 49.6%, and intraplaque hemorrhages and iron and fibrin deposition were observed frequently. TGFβRII:Fc treatment did not result in systemic effects. These results reveal a pivotal role for TGF-β in the maintenance of the balance between inflammation and fibrosis in atherosclerotic plaques.
Adverse Event Associated With Methionine Loading Test
Authors: Cottington E.M. , LaMantia Christian , Stabler Sally P. , Allen Robert H. , Tangerman Albert , Wagner Conrad , Zeisel Steven H. , Mudd S. Harvey
Published: July 2002

The death of a control subject after an oral load of methionine for a study of the possible relationship between homocysteine and Alzheimer’s disease is reported. The subject developed postload plasma concentrations of methionine far beyond those reported previously in humans given the usual oral loading dose of methionine (100 mg/kg body wt). Her preload plasma metabolite values rule out known genetic diseases that might predispose one to unusually high methionine concentrations. The most likely explanation for these events is that the subject received a substantial overdose of methionine. The possibility that extremely high methionine concentrations may lead to severe cerebral effects is discussed, and it is recommended that any move to increase the sensitivity of the usual methionine loading test by increasing the dose of methionine either not be undertaken or be taken only with extreme care.
Characterization of LDL Particle Size Among Carriers of a Defective or a Null Mutation in the Lipoprotein Lipase Gene
Authors: Ruel Isabelle L. , Gaudet Daniel , Perron Patrice , Bergeron Jean , Julien Pierre , Lamarche Benoît
Published: July 2002

Objective

—

The objective of the present study was to compare the impact of the null P207L and defective D9N mutations in the LPL gene on LDL particle size among heterozygous carriers.

Methods and Results

—

LDL particle size was measured on whole plasma by 2% to 16% non-denaturing polyacrylamide gradient gel electrophoresis in a cohort of 206 heterozygous carriers of either the P207L or the D9N mutation. The P207L carriers (N=88) presented with a more atherogenic lipoprotein-lipid profile compared with the D9N carriers (N=118). Accordingly, LDL particle size was smaller in the P207L carriers than in the D9N subjects (248.8± 1.0 vs 254.5±1.0 Å,
P
< 0.001), and the difference remained significant after adjustment for plasma triglyceride (TG) levels. The difference in LDL diameter between the P207L and the D9N carriers was 3-fold greater in individuals with plasma TG levels >3.5 mmol/L than in subjects with TG ≤3.5 mmol/L. The factors that statistically contributed to LDL particle size variation in multivariate analyses were plasma TG levels (11.6%) and age (6.4%) in subjects with TG levels ≤3.5 mmol/L and HDL cholesterol levels (15.5%) and the LPL gene mutation (null versus defective, 7.0%) in patients with TG levels >3.5 mmol/L.

Conclusions

—

These results suggest that the null P207L mutation in the LPL gene has a greater impact on LDL particle size than the defective D9N mutation and that this mutation-specific effect is amplified at greater plasma TG concentrations.
Heterogeneity of Smooth Muscle Cell Populations Cultured From Pig Coronary Artery
Authors: Hao Hiroyuki , Ropraz Patricia , Verin Vitali , Camenzind Edoardo , Geinoz Antoine , Pepper Michael S. , Gabbiani Giulio , Bochaton-Piallat Marie-Luce
Published: July 2002

Objective

—

Heterogeneous smooth muscle cell (SMC) populations have been described in the arteries of several species. We have investigated whether SMC heterogeneity is present in the porcine coronary artery, which is widely used as a model of restenosis.

Methods and Results

—

By using 2 isolation methods, distinct medial populations were identified: spindle-shaped SMCs (S-SMCs) after enzymatic digestion, with a “hill-and-valley” growth pattern, and rhomboid SMCs (R-SMCs) after explantation, which grow as a monolayer. Moreover, the intimal thickening that was induced after stent implantation yielded a large proportion of R-SMCs. R-SMCs exhibited high proliferative and migratory activities and high urokinase activity and were poorly differentiated compared with S-SMCs. Heparin and transforming growth factor-β2 inhibited proliferation and increased differentiation in both populations, whereas fibroblast growth factor-2 and platelet-derived growth factor-BB had the opposite effect. In addition, S-SMCs treated with fibroblast growth factor-2 or platelet-derived growth factor-BB or placed in coculture with coronary artery endothelial cells acquired a rhomboid phenotype. This change was reversible and was also observed with S-SMC clones, suggesting that it depends on phenotypic modulation rather than on selection.

Conclusions

—

Our results show that 2 distinct SMC subpopulations can be recovered from the pig coronary artery media. The study of these subpopulations will be useful for understanding the mechanisms of restenosis.
Mechanism of Accumulation of Cholesterol and Cholestanol in Tendons and the Role of Sterol 27-hydroxylase (CYP27A1)
Authors: von Bahr Sara , Movin Tomas , Papadogiannakis Nikos , Pikuleva Irina , Rönnow Per , Diczfalusy Ulf , Björkhem Ingemar
Published: July 2002

Objective

—

Tendon xanthomas are deposits of lipids and connective tissue commonly found in hypercholesterolemic patients. Macrophages are likely to be responsible for the lipid accumulation. Normolipidemic patients with the rare disease cerebrotendinous xanthomatosis, lacking the enzyme sterol 27-hydroxylase (CYP27A1), develop prominent xanthomas in tendons and brain containing both cholestanol and cholesterol, with a cholestanol:cholesterol ratio higher than that in the circulation. Because of its ability to convert cholesterol into polar metabolites that leave the cells faster, CYP27A1 has been suggested to be an antiatherogenic enzyme. The hypothesis was tested that tendons contain CYP27A1 that may be of importance for the normal efflux of both steroids.

Methods and Results

—

Western blotting and combined gas chromatography-mass spectrometry showed that human tendons contain significant amounts of CYP27A1 and its product, 27-hydroxycholesterol. Immunohistochemistry showed that CYP27A1 is present in macrophages and tenocytes. The tendons also contained cholestanol, with a cholestanol:cholesterol ratio slightly higher than that in the circulation. Recombinant human CYP27A1, and cultured human macrophages containing this enzyme, had similar activity toward cholesterol and cholestanol. After loading of macrophages with labeled cholesterol and cholestanol, there was an efflux of these steroids in both unmetabolized and 27-oxygenated form, resulting in a significant cellular accumulation of cholestanol compared with cholesterol.

Conclusion

—

The results are consistent with the possibility that CYP27A1 is of importance for the efflux of both cholesterol and cholestanol from tendons.
Human Secretory Phospholipase A2Mediates Decreased Plasma Levels of HDL Cholesterol and ApoA-I in Response to Inflammation in Human ApoA-I Transgenic Mice
Authors: Tietge Uwe J.F. , Maugeais Cyrille , Lund-Katz Sissel , Grass David , deBeer Frederick C. , Rader Daniel J.
Published: July 2002

Objective—Plasma levels of high density lipoprotein (HDL) cholesterol and apolipoprotein (apo)A-I are decreased in inflammatory states. Secretory phospholipase A2(sPLA2), an acute-phase protein, may play a key role in the pathophysiology of this phenomenon.

Methods and Results—To investigate the effects of sPLA2on human-like HDL particles in vivo, we generated transgenic mice overexpressing human apoA-I and human sPLA2(apoA-I/sPLA2mice). Compared with apoA-I mice, apoA-I/sPLA2mice had significantly lower plasma levels of phospholipids, HDL cholesterol, and apoA-I (eachP<0.01). HDL from apoA-I/sPLA2mice was significantly depleted in phospholipids and cholesteryl esters (eachP<0.001) but was enriched in protein and triglycerides (eachP<0.001). As assessed by gel filtration and nondenaturing gel electrophoresis, sPLA2overexpression in apoA-I mice resulted in a dramatic shift of the HDL particle size toward smaller particles. Furthermore, virtually all plasma sPLA2in apoA-I/sPLA2mice was found in association with the HDL fraction. The acute-phase response was induced in apoA-I/sPLA2double-transgenic and apoA-I single-transgenic mice by intraperitoneal lipopolysaccharide (LPS) injection. Plasma sPLA2was significantly increased after LPS injection in apoA-I/sPLA2mice. Twelve hours after LPS administration, plasma total cholesterol, HDL cholesterol, apoA-I, and phospholipids were unchanged in apoA-I transgenic control mice but had decreased significantly in the apoA-I/sPLA2mice (−57%, −62%, and −54%, −61%, respectively; eachP<0.001). Both groups of mice had increased plasma levels of serum amyloid A (SAA) in response to LPS. To test the hypothesis that SAA may be an in vivo activator of sPLA2, we specifically overexpressed SAA in apoA-I/sPLA2mice by means of liver-directed gene transfer. Despite high plasma levels of SAA, plasma lipid and lipoprotein profiles were not different than those in control mice.

Conclusions—These results in a mouse model of human-like HDL indicate that sPLA2expression significantly influences HDL particle size and composition and demonstrate that an induction of sPLA2is required for the decrease in plasma HDL cholesterol in response to inflammatory stimuli in mice and that this effect is independent of SAA.
High-Dose Intravascular β-Radiation After De Novo Stent Implantation Induces Coronary Artery Spasm
Authors: Scheinert D. , Strnad V. , Müller R. , Burckhard R. , Ropers S. , Sauer R. , Daniel W.G. , Bonan R. , Ludwig J.
Published: July 2002

Background

—

Intracoronary brachytherapy is effective in preventing restenosis after coronary interventions. However, in vitro and animal studies have shown that irradiation produces immediate and sustained endothelial dysfunction. This study assesses the clinical relevance of impaired vasomotoric function induced by brachytherapy.

Methods and Results

—

We analyzed the occurrence of postradiation coronary artery spasms in 1 animal study and 2 clinical trials investigating the effects of high-dose intracoronary β-radiation after de novo coronary artery stenting. Irradiated segments (IRSs) proximal and distal to the stent were studied by quantitative coronary angiography after stenting, after radiation, and at the end of the procedure. There was an 67% overall incidence of coronary artery spasm in the IRSs immediately after β-radiation compared with 9% after sham treatment (
P
<0.001). Whereas in most cases this phenomenon was only minor or moderate, in 12 cases, 4 (22%) animals and 8 (28%) patients, severe coronary spasm (>90% diameter stenosis) with significant ECG-changes or hemodynamic instability was observed. Relief of spasms was protracted (mean time until complete relief of spasm 423±122 seconds) and required repetitive intracoronary administration of nitroglycerin (mean dose: 1.2±0.6 mg).

Conclusions

—

Vasoconstriction is a frequent reaction of coronary arteries after high-dose intracoronary β-radiation, necessitating repetitive administration of vasodilators.
In Vivo Temperature Heterogeneity of Atherosclerotic Plaques Is Determined by Plaque Composition
Authors: Verheye Stefan , De Meyer Guido R.Y. , Van Langenhove Glenn , Knaapen Michiel W.M. , Kockx Mark M.
Published: July 2002

Background

—

Temperature heterogeneity of atherosclerotic plaques has been associated with macrophage accumulation in ex vivo studies. We investigated in vivo whether modifying the cell composition of rabbit atherosclerotic plaques by dietary cholesterol lowering can influence temperature heterogeneity.

Methods and Results

—

Twenty New Zealand rabbits were randomized to either a normal (n=10) or cholesterol-rich (0.3%) diet (n=10) for 6 months. Thereafter, intravascular ultrasound and intravascular catheter-based thermography of the surface of aortic arch and descending aorta were performed in all animals. Ten control and 5 hypercholesterolemic rabbits were euthanized, and their aortas were analyzed histologically. The 5 remaining rabbits received a normal diet for 3 months and underwent repeat ultrasound and thermography before euthanasia followed by histology. Ex vivo temperature was measured in 3 additional rabbits at 6 months to correlate local temperature with local plaque composition. In control animals, plaque formation and temperature heterogeneity were absent. In hypercholesterolemic rabbits, plaque formation was prominent in the thoracic aorta. Plaques were composed of fibromuscular tissue and contained, underneath endothelial cells, an accumulation of foam cells of macrophage origin. Temperature heterogeneity was markedly elevated and increased with plaque thickness. Importantly, after 3 months of cholesterol lowering, plaque thickness remained unchanged, but temperature heterogeneity was significantly decreased. This paralleled plaque histology, which showed a marked loss of macrophages. The ex vivo experiments demonstrated the relation between local temperature and local total macrophage mass.

Conclusions

—

In vivo temperature heterogeneity of rabbit atherosclerotic plaques is determined by plaque composition. In vivo thermography may have important clinical implications in the assessment of plaque composition.
Nitric Oxide Mediates the Antiapoptotic Effect of Insulin in Myocardial Ischemia-Reperfusion
Authors: Gao Feng , Gao Erhe , Yue Tian-Li , Ohlstein Eliot H. , Lopez Bernard L. , Christopher Theodore A. , Ma Xin-Liang
Published: July 2002

Background—

Recent evidence from cultured endothelial cell studies suggests that phosphorylation of endothelial nitric oxide synthase (eNOS) through the PI3-kinase–
Akt
pathway increases NO production. This study was designed to elucidate the signaling pathway involved in the antiapoptotic effect of insulin in vivo and to test the hypothesis that phosphorylation of eNOS by insulin may participate in the cardioprotective effect of insulin after myocardial ischemia and reperfusion.

Methods and Results—

Male Sprague-Dawley rats were subjected to 30 minutes of myocardial ischemia and 4 hours of reperfusion. Rats were randomized to receive vehicle, insulin, insulin plus wortmannin, or insulin plus L-NAME. Treatment with insulin resulted in 2.6-fold and 4.3-fold increases in
Akt
and eNOS phosphorylation and a significant increase in NO production in ischemic/reperfused myocardial tissue. Phosphorylation of
Akt
and eNOS and increase of NO production by insulin were completely blocked by wortmannin, a PI3-kinase inhibitor. Pretreatment with L-NAME, a nonselective NOS inhibitor, had no effect on
Akt
and eNOS phosphorylation but significantly reduced NO production. Moreover, treatment with insulin markedly reduced myocardial apoptotic death (
P
<0.01 versus vehicle). Pretreatment with wortmannin abolished the antiapoptotic effect of insulin. Most importantly, pretreatment with L-NAME also significantly reduced the antiapoptotic effect of insulin (
P
<0.01 versus insulin).

Conclusions—

These results demonstrated that in vivo administration of insulin activated
Akt
through the PI3-kinase–dependent mechanism and reduced postischemic myocardial apoptotic death. Phosphorylation of eNOS and the concurrent increase of NO production contribute significantly to the antiapoptotic effect of insulin.
Inflammation and Long-Term Mortality After Non–ST Elevation Acute Coronary Syndrome Treated With a Very Early Invasive Strategy in 1042 Consecutive Patients
Authors: Mueller Christian , Buettner Heinz J. , Hodgson John M. , Marsch Stephan , Perruchoud André P. , Roskamm Helmut , Neumann Franz-Josef
Published: July 2002

Background

—

This study sought to evaluate the predictive value of C-reactive protein (CRP) on long-term mortality in non–ST-elevation acute coronary syndromes (NSTACS) that were treated with a very early aggressive revascularization strategy.

Methods and Results

—

We conducted a prospective cohort study in 1042 consecutive patients with NSTACS who were undergoing coronary angiography and subsequent coronary stenting of the culprit lesion as the primary revascularization strategy within 24 hours. Levels of CRP were determined on admission. The patients were followed for a mean of 20 months. In-hospital mortality was significantly higher in patients with a CRP>10 mg/L (3.7% versus 1.2% with CRP<3 mg/L and versus 0.8% with CRP of 3 to 10 mg/L; relative risk for CRP>10 mg/L compared with CRP≤10 mg/L was 4.2, 95% confidence interval [CI] was 1.6 to 11.0;
P
=0.004). The increase in mortality in patients with CRP>10 mg/L persisted during follow-up. Long-term mortality was 3.4% with CRP<3 mg/L, 4.4% with CRP between 3 and 10 mg/L, and 12.7% with CRP>10 mg/L (relative risk for CRP>10 mg/L compared with CRP≤10 mg/L, 0.8; 95% CI, 2.3 to 6.2;
P
<0.001). In addition, Kaplan-Meier survival analysis demonstrated a significantly reduced survival at 4 years in patients with a CRP>10 mg/L (78% versus 88% for a CRP of 3 to 10 mg/L and versus 92% for CRP<3 mg/L;
P
<0.001 by log-rank). In a multivariate analysis, CRP was an independent predictor of long-term mortality. Patients with a CRP>10 mg/L had >4 times the risk of death (odds ratio, 4.1; 95% CI, 2.3 to 7.2).

Conclusion

—

CRP is a strong independent predictor of short and long-term mortality after NSTACS that are treated with very early revascularization.
Markers of Increased Risk of Intracerebral Hemorrhage After Intravenous Recombinant Tissue Plasminogen Activator Therapy for Acute Ischemic Stroke in Clinical Practice
Authors: Tanne David , Kasner Scott E. , Demchuk Andrew M. , Koren-Morag Nira , Hanson Sandra , Grond Martin , Levine Steven R. ,   the Multicenter rt-PA Stroke Survey Group
Published: July 2002

Background

—

Intravenous recombinant tissue plasminogen activator (rtPA) is an effective therapy for acute ischemic stroke, but it is associated with risk of intracerebral hemorrhage (ICH). Our aim was to identify, in a large cohort of patients, readily available baseline factors that are associated with thrombolysis-related ICH.

Methods and Results

—

In a multicenter retrospective and prospective investigation of individual data from 1205 patients treated in routine clinical practice with intravenous rtPA within 3 hours of stroke symptom onset, 72 patients (6%) developed symptomatic ICH and 86 additional patients (7%) had asymptomatic ICH identified on a routine follow-up CT. In analyses based on clinical variables alone, the main attributes associated with ICH were a history of diabetes mellitus and cardiac disease, increasing stroke severity, advancing age, use of antiplatelet agents other than aspirin before stroke onset, and elevated pretreatment mean blood pressure. In additional analyses that incorporated baseline CT and laboratory findings (in a subset of patients), the main associations were early ischemic CT changes, in particular if exceeding one third of middle cerebral artery territory; increasing stroke severity; diabetes mellitus or elevated serum glucose; and lower platelet counts. Final independent attributes associated with parenchymatous hematoma, defined by purely radiologically based criteria, were similar to those of symptomatic ICH.

Conclusions

—

Readily available factors can identify acute ischemic stroke patients at high and low risk for rtPA-related ICH. These factors require confirmation in a prospective cohort before clinical implementation.
Tissue Doppler Imaging Differentiates Physiological From Pathological Pressure-Overload Left Ventricular Hypertrophy in Rats
Authors: Derumeaux Geneviève , Mulder Paul , Richard Vincent , Chagraoui Abdeslam , Nafeh Catherine , Bauer Fabrice , Henry Jean-Paul , Thuillez Christian
Published: July 2002

Background

—

The myocardial velocity gradient (MVG) is a recent index of regional myocardial function derived from endocardial and epicardial velocities obtained by tissue Doppler imaging (TDI). This index might be useful for discriminating between physiological and pathological left ventricular hypertrophy (LVH) and for documenting the early transition from compensated LVH to heart failure. We sought to compare MVG measured across the left ventricular posterior wall between normal rats and rats with physiological (exercise) and pathological (pressure-overload) LVH.

Methods and Results

—

Wistar rats were assigned to one of the following groups: sedentary, exercise (swimming), and 2-month or 9-month abdominal aortic banding. Compared with sedentary rats, exercise and 2-month banding led to similar and significant LVH. After 2-month banding, conventional parameters of systolic function (left ventricular fractional shortening and dP/dt
max
) were not affected. However, systolic and diastolic MVG were similar in exercise and sedentary rats but were significantly lower in rats with aortic banding. Aortic debanding after 2 months led to a full recovery of MVG, whereas MVG remained decreased when debanding was performed after 9 months.

Conclusions

—

Myocardial contraction and relaxation assessed by TDI were impaired in pressure-overload LVH but not in exercise LVH. Therefore, TDI is more sensitive than conventional echocardiography for assessing myocardial dysfunction in pressure-overload LVH and for predicting early recovery in myocardial function after loading conditions normalization.
Rebuilding a Damaged Heart
Authors: Müller-Ehmsen Jochen , Peterson Kirk L. , Kedes Larry , Whittaker Peter , Dow Joan S. , Long Tiffany I. , Laird Peter W. , Kloner Robert A.
Published: July 2002

Background—

The long-term effects of cardiac cell transplantation on cardiac function are unknown. Therefore, we tested the survival and functional impact of rat neonatal cardiac myocytes up to 6 months after transplantation into infarcted hearts.

Methods and Results—

Cardiomyocytes from male neonatal Fischer 344 rats (1 to 2 days, 3 to 5×10
6
) or medium was injected into the infarcts of adult syngeneic female animals 1 week after left coronary artery ligation. Six months later, implanted cardiomyocytes were still present by quantitative TaqMan polymerase chain reaction and histology. In all treated hearts, discrete lumps of cells were present within the infarct scar, which was not observed in media-injected hearts typified by a transmural infarct scar. Infarct thickness was greater in treated animals versus control animals (909±97 versus 619±43 μm,
P
<0.02), whereas infarct size and left ventricular volumes were similar. By biplane angiography, left ventricular ejection fractions at 6 months were greater (0.36±0.03 versus 0.25±0.02,
P
<0.01) and significantly less infarct zone dyskinesis was seen (0.30±0.08 versus 0.55±0.07,
P
=0.035, lateral projection) in treated animals versus control animals.

Conclusions—

Grafted neonatal cardiomyocytes were present in infarcts 6 months after transplantation; they thickened the wall of the left ventricle and were associated with enhanced ejection fraction and reduced paradoxical systolic bulging of the infarct. Therefore, neonatal cardiac cell transplants exhibit long-term survival in a myocardial infarct model and contribute to long-term improved cardiac function. These results suggest that a damaged heart can be rebuilt.
Inhibition of Calcineurin and Sarcolemmal Ca
2+
Influx Protects Cardiac Morphology and Ventricular Function in K
v
4.2N Transgenic Mice
Authors: Sah Rajan , Oudit Gavin Y. , Nguyen The-Tin T. , Lim Hae W. , Wickenden Alan D. , Wilson Gregory J. , Molkentin Jeffery D. , Backx Peter H.
Published: July 2002

Background
—

Cardiac-targeted expression of truncated K
v
4.2 subunit (K
v
4.2N) reduces transient outward current (
I
to
) density, prolongs action potentials (APs), and enhances contractility in 3- to 4-week-old transgenic mice. By 13 to 15 weeks of age, these mice develop severely impaired cardiac function and signs of heart failure. In this study, we examined whether augmented contractility in K
v
4.2N mice results from elevations in intracellular calcium ([Ca
2+
]
i
) secondary to AP prolongation and investigated the putative roles of calcineurin activation in heart disease development of K
v
4.2N mice.

Methods and Results
—

At 3 to 4 weeks of age, L-type Ca
2+
influx and peak [Ca
2+
]
i
were significantly elevated in K
v
4.2N myocytes compared with control because of AP prolongation. Cardiac calcineurin activity was also significantly elevated in K
v
4.2N mice by 5 weeks of age relative to controls and increased progressively as heart disease developed. This was associated with activation of protein kinase C (PKC)-α and PKC-θ but not PKC-ε, as well as increases in β-myosin heavy chain (β-MHC) and reductions in sarcoplasmic/endoplasmic reticulum Ca
2+
-ATPase (SERCA)-2a expression. Treatment with either cyclosporin A or verapamil prevented increases in heart weight to body weight ratios, interstitial fibrosis, impaired contractility, PKC activation, and changes in the expression patterns of β-MHC and SERCA2a.

Conclusions
—

Our results demonstrate that AP prolongation caused by
I
to
reduction results in enhanced Ca
2+
cycling and hypercontractility in mice and suggests that elevations in [Ca
2+
]
i
via
I
Ca,L
and activation of calcineurin play a central role in disease development after
I
to
reduction using the K
v
4.2N construct.
Enhanced Expression of the LDL Receptor Family Member LR11 Increases Migration of Smooth Muscle Cells In Vitro
Authors: Zhu Yanjuan , Bujo Hideaki , Yamazaki Hiroyuki , Hirayama Satoshi , Kanaki Tatsuro , Takahashi Kazuo , Shibasaki Manabu , Schneider Wolfgang J. , Saito Yasushi
Published: July 2002

Background
—

LR11, a member of the LDL receptor family, is highly expressed in vascular smooth muscle cells (SMCs) of the hyperplastic intima but not media. To further clarify the involvement of LR11 in the process of atherosclerosis, we have characterized the migration and invasion activities of LR11-overexpressing SMCs.

Methods and Results
—

LR11 cDNA was transfected into the rat SMC line A7r5. Compared with mock cells (C-1), in the presence of platelet-derived growth factor-BB, the transfected cells (R-1 and R-2) showed 3.5- to 4.0-fold higher expression of LR11 protein, 1.7- to 1.8-fold increased migration, and 2.0- to 2.2-fold elevated invasion activities, respectively. The increases were essentially abolished by the addition of receptor-associated protein, anti-LR11 antibodies, or apolipoprotein E. Immunological analyses showed that urokinase-type plasminogen activator receptor (uPAR) levels were increased in LR11-overexpressing cells. Anti–urokinase-type plasminogen activator (uPA) and anti-uPAR antibodies reduced the migration and invasion activities of R-1 and R-2 cells to baseline levels. Receptor-associated protein, anti-LR11 antibodies, and apolipoprotein E decreased uPAR expression in the LR11-overexpressing cells by ≈50%. Cellular catabolism of uPAR was significantly decreased in R-1 and R-2 cells compared with control. Cultured SMCs isolated from intima of atherosclerotic rabbit aortas showed increased expression levels of LR11 and uPAR and enhanced migration and invasion compared with SMCs from medial layers.

Conclusions
—

Overexpression of LR11 induces enhanced migration and invasion activities of intimal SMCs in vitro, probably through its regulation of the uPA/uPAR system.
Continuous Probabilistic Prediction of Angiographically Significant Coronary Artery Disease Using Electron Beam Tomography
Authors: Budoff Matthew J. , Diamond George A. , Raggi Paolo , Arad Yadon , Guerci Alan D. , Callister Tracy Q. , Berman Daniel
Published: July 2002

Background
—

We sought to incorporate electron beam tomography–derived calcium scores in a model for prediction of angiographically significant coronary artery disease (CAD). Such a model could greatly facilitate clinical triage in symptomatic patients with no known CAD.

Methods and Results
—

We examined 1851 patients with suspected CAD who underwent coronary angiography for clinical indications. An electron beam tomographic scan was performed in all patients. Total per-patient calcium scores and separate scores for the major coronary arteries were added to logistic regression models to calculate a posterior probability of the severity and extent of angiographic disease. These models were designed to be continuous, adjusted for age and sex, corrected for verification bias, and independently validated in terms of their incremental diagnostic accuracy. The overall sensitivity was 95%, and specificity was 66% for coronary calcium to predict obstructive disease on angiography. With calcium scores >20, >80, and >100, the sensitivity to predict stenosis decreased to 90%, 79%, and 76%, whereas the specificity increased to 58%, 72%, and 75%, respectively. The logistic regression model exhibited excellent discrimination (receiver operating characteristic curve area, 0.842±0.023) and calibration (χ
2
goodness of fit, 8.95;
P
=0.442).

Conclusions
—

Electron beam tomographic calcium scanning provides incremental and independent power in predicting the severity and extent of angiographically significant CAD in symptomatic patients, in conjunction with pretest probability of disease. This algorithm is most useful when applied to an intermediate-risk population.
Comparative Antithrombotic Effects of Magnesium Sulfate and the Platelet Glycoprotein IIb/IIIa Inhibitors Tirofiban and Eptifibatide in a Canine Model of Stent Thrombosis
Authors: Rukshin Vladimir , Shah Prediman K. , Cercek Bojan , Finkelstein Ariel , Tsang Vivian , Kaul Sanjay
Published: July 2002

Background

—

Antithrombotic effects of glycoprotein IIb/IIIa inhibitors and magnesium are known, but their comparative effects on stent thrombosis are not known. Our objective was to compare the antithrombotic effects of the glycoprotein IIb/IIIa inhibitors tirofiban and eptifibatide with magnesium in an ex vivo canine arteriovenous shunt model of stent thrombosis.

Methods and Results

—

Control nitinol stents were expanded to 2 mm in diameter in a tubular perfusion chamber interposed in the shunt and exposed to flowing arterial blood at a shear rate of 2100 s
−1
for 20 minutes (n=398 perfusion runs in 24 experiments in 8 dogs). The animals were treated intravenously with MgSO
4
(2 g bolus×20 minutes followed by 2 g/h infusion), eptifibatide (double bolus of 180 μg/kg 10 minutes apart followed by 2 μg/kg per minute), or tirofiban (0.3 μg/kg per minute), with or without heparin (50 U/kg). Effects of the test agents on thrombus weight, platelet aggregation (PA), platelet CD62 expression, bleeding time (BT), heart rate, and mean arterial blood pressure were assessed. Treatment with Mg+heparin reduced stent thrombus weight by 78±10% compared with baseline (19±4 mg,
P
<0.001). The antithrombotic effect of Mg+heparin was equivalent to that observed with tirofiban+heparin (78±13%) and eptifibatide+heparin (84±11%). Magnesium had no significant effect on PA and BT. Tirofiban and eptifibatide inhibited PA by >90% and prolonged BT up to 20 minutes. None of the test agents had effects on CD62 expression or activated clotting time. There were no significant bleeding or hemodynamic complications.

Conclusion

—

Magnesium produced a significant reduction in acute stent thrombus formation that was equivalent in magnitude to that produced by clinically relevant doses of tirofiban and eptifibatide. Its potential use in percutaneous coronary intervention requires further study.
Enhanced Activity of Variant Phospholipase C-δ1 Protein (R257H) Detected in Patients With Coronary Artery Spasm
Authors: Nakano Takao , Osanai Tomohiro , Tomita Hirofumi , Sekimata Masayuki , Homma Yoshimi , Okumura Ken
Published: July 2002

Background

—

We recently demonstrated that phospholipase C (PLC)–δ1 activity in cultured skin fibroblasts obtained from patients with coronary spastic angina (CSA) is enhanced. We tested the hypothesis that structural abnormality in PLC-δ1 isoform is a cause of the enhanced activity.

Methods and Results

—

Sequence analysis of the cDNA coding for PLC-δ1 obtained from fibroblasts revealed that one conversion of guanine to adenine (A) was present at nucleotide position 864 in one CSA patient, resulting in the amino acid replacement of arginine 257 by histidine (R257H). The incidence of 864A/A in genomic DNA, analyzed by single-strand conformation polymorphism, was greater in patients with CSA than in male control subjects (6 of 57 patients with CSA versus 1 of 62 control subjects,
P
<0.05). The activity of the variant PLC-δ1 protein under free calcium concentration between 10
−8
and 10
−7
mol/L was 2-fold higher than that of the wild-type protein. Baseline intracellular calcium concentration ([Ca
2+
]
i
) in human embryonic kidney 293 cells transfected with the variant PLC-δ1 was higher than that in cells with the wild type. The peak increase in [Ca
2+
]
i
in response to acetylcholine at 10
−6
and 10
−5
mol/L was greater in the cells with the variant PLC-δ1 than in those with the wild type.

Conclusions

—

These findings indicate that the R257H variant in the PLC-δ1 gene detected in patients with CSA is associated with enhancement of enzyme activity, and they describe a novel mechanism for the enhanced coronary vasomotility in CSA.
Direct Evidence for Tumor Necrosis Factor-α Signaling in Arteriogenesis
Authors: Hoefer Imo E. , van Royen Niels , Rectenwald John E. , Bray Elizabeth J. , Abouhamze Zaher , Moldawer Lyle L. , Voskuil Michiel , Piek Jan J. , Buschmann Ivo R. , Ozaki C. Keith
Published: July 2002

Background

—

Arteriogenesis serves as an efficient mechanism for flow restoration after arterial occlusion. This process is associated with inflammatory mediators such as tumor necrosis factor-α (TNF-α), although their role in arteriogenesis remains unclear. We hypothesized that arteriogenesis is reduced in mice lacking functional TNF-α or p55 receptor. To test this hypothesis, we developed a novel microsphere-based murine model of hindlimb perfusion measurement.

Methods and Results

—

Unilateral femoral arteries of nude (n=9), TNF-α
−/−
(n=9), TNF-α receptor p55
−/−
(n=8), and p75
−/−
(n=8) mice as well as their appropriate genetic background controls were occluded. The nude mice underwent laser Doppler hindlimb flux measurements preoperatively, postoperatively, and after 7 days. Seven days after ligation, all animals underwent tissue perfusion determinations using fluorescent microspheres. Laser Doppler findings confirmed acute decrease in flux with falsely normal values after 1 week. Microsphere results from control mice showed perfusion restoration to values ≈50% of normal within 7 days. TNF-α
−/−
mice demonstrated a significant reduction (45.1%) in collateral artery perfusion compared with controls (TNF-α
−/−
22.4±5.1% versus B6x129 49.7±9.3%;
P
<0.01). p55
−/−
mice exhibited an almost identical 45.8% reduction in collateral artery formation (p55
−/−
28.3±4.3% versus C57BL/6J 61.8±9.1%;
P
<0.01), whereas p75
−/−
mice were equivalent to controls (p75
−/−
54.5±5.5%;
P
=0.13).

Conclusions

—

Microsphere techniques in mice offer a tool for the molecular dissection of arteriogenesis mechanisms. These results suggest that TNF-α positively modulates arteriogenesis probably via signaling through its p55 receptor.
Foam Cell Formation Inhibits Growth of

Chlamydia pneumoniae

but Does Not Attenuate

Chlamydia pneumoniae

–Induced Secretion of Proinflammatory Cytokines
Authors: Blessing Erwin , Kuo Cho-chou , Lin Tsun-Mei , Campbell Lee Ann , Bea Florian , Chesebro Brian , Rosenfeld Michael E.
Published: July 2002

Background

—

It has not yet been determined whether lipid-loaded macrophages (foam cells), a major cellular component of atherosclerotic lesions, have the capacity to support growth of
Chlamydia pneumoniae
and be activated to secrete proinflammatory cytokines in response to
C pneumoniae
infection.

Methods and Results

—

Lipid loading of RAW 264.7 cells and mouse peritoneal macrophages with either oxidized or acetylated LDL significantly inhibits the growth of
C pneumoniae.
Modified forms of LDL are not directly toxic to
C pneumoniae
and do not inhibit either the initial binding or internalization of
C pneumoniae
by macrophages. Lipid loading does not reduce infection of macrophages with
Chlamydia trachomatis
. Treatment of lipid-loaded macrophages with live, heat-killed, or UV-inactivated
C pneumoniae
stimulates secretion of cytokines.
C pneumoniae
also induces expression of the mRNA for tumor necrosis factor-α in foam cells despite inhibition of nuclear factor-κB binding to DNA by prior treatment with oxidized LDL.

Conclusions

—

Foam cell formation is not conducive to growth of
C pneumoniae
but does not inhibit the
C pneumoniae
–induced secretion of proinflammatory cytokines.
Elevated C-Reactive Protein Values and Atherosclerosis in Sudden Coronary Death
Authors: Burke Allen P. , Tracy Russell P. , Kolodgie Frank , Malcom Gray T. , Zieske Arthur , Kutys Robert , Pestaner Joseph , Smialek John , Virmani Renu
Published: July 2002

Background

—

Elevations in serum C-reactive protein measured by high-sensitivity assay (hs-CRP) have been associated with unstable coronary syndromes. There have been no autopsy studies correlating hs-CRP to fatal coronary artery disease.

Methods and Results

—

Postmortem sera from 302 autopsies of men and women without inflammatory conditions other than atherosclerosis were assayed for hs-CRP. There were 73 sudden deaths attributable to atherothrombi, 71 sudden coronary deaths with stable plaque, and 158 control cases (unnatural sudden deaths and noncardiac natural deaths without conditions known to elevate CRP). Atherothrombi were classified as plaque ruptures (n=55) and plaque erosion (n=18); plaque burden was estimated in each heart. Total cholesterol, high-density lipoprotein cholesterol, diabetes, smoking history, and body mass index were also determined. Immunohistochemical stains for CRP and numbers of thin cap atheromas per heart were quantitated in coronary deaths with hs-CRP in the highest and lowest quintiles. The median hs-CRP was 3.2 μg/mL in acute rupture, 2.9 μg/mL in plaque erosion, 2.5 μg/mL in stable plaque, and 1.4 μg/mL in controls. Mean log hs-CRP was higher in rupture (
P
<0.0001), erosion (
P
=0.005), and stable plaque (
P
=0.0003) versus controls. By multivariate analysis, atherothrombi (
P
=0.02), stable plaque (
P
=0.003), and plaque burden (
P
=0.03) were associated with log hs-CRP independent of age, sex, smoking, and body mass index. Mean staining intensity for CRP of macrophages and lipid core in plaques was significantly greater in cases with high hs-CRP than those with low CRP (
P
=0.0001), as were mean numbers of thin cap atheromas (
P
<0.0001).

Conclusions

—

hs-CRP is significantly elevated in patients dying suddenly with severe coronary artery disease, both with and without acute coronary thrombosis, and correlates with immunohistochemical staining intensity and numbers of thin cap atheroma.
Inhibition of Tissue Factor Gene Induction and Activity Using a Hairpin Ribozyme
Authors: Cavusoglu Erdal , Chen Irene , Rappaport Jay , Marmur Jonathan D.
Published: July 2002

Background

—

Tissue factor (TF) is a membrane-bound glycoprotein that initiates the clotting cascade. Inhibition of the TF pathway has been shown to prevent thrombosis and restenosis after arterial injury in a variety of animal models.

Methods and Results

—

We describe a novel approach to inhibiting the expression of the TF protein that involves the targeted destruction of cellular TF mRNA with the use of a tetraloop hairpin ribozyme. After construction of the ribozyme and determination of its optimal length and kinetic parameters, a ribozyme expression vector that used the retroviral vector pMV12 was constructed. The ability of this expression vector to generate anti-TF ribozyme was further augmented by positioning of the anti-TF ribozyme downstream of a rat tRNA val (RNA polymerase II) promoter. The resultant construct containing the anti-TF ribozyme was then used to transfect vascular smooth muscle cells and generate a variety of clonal cell lines. Northern blot analyses performed on 3 transfected and 3 untransfected clones demonstrated markedly reduced TF mRNA levels in the transfected clones both during quiescence and after serum stimulation. Cell lysates analyzed for total TF activity by monitoring factor Xa generation similarly demonstrated a statistically significant and concordant reduction in TF activity in smooth muscle cells transfected with the ribozyme expression vector compared with both untransfected clones and clones transfected with the empty vector.

Conclusions

—

These results demonstrate the feasibility of an antithrombotic strategy based on ribozyme technology.
Incidence and Prognostic Importance of Acute Renal Failure After Percutaneous Coronary Intervention
Authors: Rihal Charanjit S. , Textor Stephen C. , Grill Diane E. , Berger Peter B. , Ting Henry H. , Best Patricia J. , Singh Mandeep , Bell Malcolm R. , Barsness Gregory W. , Mathew Verghese , Garratt Kirk N. , Holmes David R.
Published: July 2002

Background

—

In patients undergoing percutaneous coronary intervention (PCI) in the modern era, the incidence and prognostic implications of acute renal failure (ARF) are unknown.

Methods and Results

—

With a retrospective analysis of the Mayo Clinic PCI registry, we determined the incidence of, risk factors for, and prognostic implications of ARF (defined as an increase in serum creatinine [Cr] >0.5 mg/dL from baseline) after PCI. Of 7586 patients, 254 (3.3%) experienced ARF. Among patients with baseline Cr <2.0, the risk of ARF was higher among diabetic than nondiabetic patients, whereas among those with a baseline Cr >2.0, all had a significant risk of ARF. In multivariate analysis, ARF was associated with baseline serum Cr, acute myocardial infarction, shock, and volume of contrast medium administered. Twenty-two percent of patients with ARF died during the index hospitalization compared with only 1.4% of patients without ARF (
P
<0.0001). After adjustment, ARF remained strongly associated with death. Among hospital survivors with ARF, 1- and 5-year estimated mortality rates were 12.1% and 44.6%, respectively, much greater than the 3.7% and 14.5% mortality rates in patients without ARF (
P
<0.0001).

Conclusions

—

The overall incidence of ARF after PCI is low. Diabetic patients with baseline Cr values <2.0 mg/dL are at higher risk than nondiabetic patients, whereas all patients with a serum Cr >2.0 are at high risk for ARF. ARF was highly correlated with death during the index hospitalization and after dismissal.