bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for a Dystrophin Missense Mutation as a Cause of X-Linked Dilated Cardiomyopathy
Authors: Ortiz-Lopez Rocio , Li Hua , Su Jason , Goytia Veronica , Towbin Jeffrey A.
Published: June 2012

Background
X-linked dilated cardiomyopathy (XLCM) has previously been shown to be due to mutations in the dystrophin gene, which is located at Xp21. Mutations in the 5′ portion of the gene, including the muscle promoter, exon 1, and the exon 1–intron 1 splice site, have been reported previously. The purpose of this study was to analyze the originally described family with XLCM (and others) for dystrophin mutations.

Methods and Results
Polymerase chain reaction (PCR) was used to amplify genomic DNA, and reverse-transcriptase PCR amplified cDNA from RNA obtained from heart and lymphoblastoid cell lines. Primers to the muscle promoter, brain promoter, and Purkinje cell promoter were designed, in addition to the exon 1 to exon 14 regions of dystrophin. Single-strand conformation polymorphism analysis was used for mutation detection, and DNA sequencing defined the mutation. Protein modeling was used for amino acid and secondary structure analysis. A missense mutation in exon 9 at nucleotide 1043 was identified that causes an alanine to be substituted for threonine, a highly conserved amino acid, at position 279 (T279A). This mutation results in a change in polarity in the evolutionarily conserved first hinge region (H1) of the protein and substitution of a β-sheet for α-helix in this portion of the protein, destabilizing the protein.

Conclusions
A novel missense mutation in exon 9 of dystrophin causing an abnormality at H1 leads to the cardiospecific phenotype of XLCM.
Relation of Operator Volume and Experience to Procedural Outcome of Percutaneous Coronary Revascularization at Hospitals With High Interventional Volumes
Authors: Ellis Stephen G. , Weintraub William , Holmes David , Shaw Richard , Block Peter C. , King Spencer B.
Published: June 2012

Background
Although an inverse relation between physician caseload and complications has been conclusively demonstrated for several surgical procedures, such data are lacking for percutaneous coronary intervention, and the ACC/AHA guidelines requiring ≥75 cases per year for operator “competency” are considered by some physicians to be arbitrary.

Methods and Results
From quality-controlled databases at five high-volume centers, models predictive of death and the composite outcome of death, Q-wave infarction, or emergency bypass surgery were developed from 12 985 consecutively treated patients during 1993 through 1994. Models had moderate to high discriminative capacity (area under ROC curves, 0.65 to 0.85), were well calibrated, and were not overfitted by standard tests. These models were used for risk adjustment, and the relations between both yearly caseload and years of interventional experience and the two adverse outcome measures were explored for all 38 physicians with ≥30 cases per year. The average physician performed a mean±SD of 163±24 cases per year and had been practicing angioplasty for 8±5 years. Risk-adjusted measures of both death and the composite adverse outcome were inversely related to the number of cases each operator performed annually but bore no relation to total years of experience. Both adverse outcomes were more closely related to the logarithm of caseload (for death,
r
=.37,
P
=.01; for death, Q-wave infarction, or bypass surgery,
r
=.58,
P
<.001) than to linear caseload.

Conclusions
In this analysis, high-volume operators had a lower incidence of major complications than did lower-volume operators, but the difference was not consistent for all operators. If these data are validated, their implications for hospital, physician, and payer policy will require exploration.
Relationship Between Physician and Hospital Coronary Angioplasty Volume and Outcome in Elderly Patients
Authors: Jollis James G. , Peterson Eric D. , Nelson Charlotte L. , Stafford Judith A. , DeLong Elizabeth R. , Muhlbaier Lawrence H. , Mark Daniel B.
Published: June 2012

Background
With the expectation that physicians who perform larger numbers of coronary angioplasty procedures will have better outcomes, the American College of Cardiology/American Heart Association guidelines recommend minimum physician volumes of 75 procedures per year. However, there is little empirical data to support this recommendation.

Methods and Results
We examined in-hospital bypass surgery and death after angioplasty according to 1992 physician and hospital Medicare procedure volume. In 1992, 6115 physicians performed angioplasty on 97 478 Medicare patients at 984 hospitals. The median numbers of procedures performed per physician and per hospital were 13 (interquartile range, 5 to 25) and 98 (interquartile range, 40 to 181), respectively. With the assumption that Medicare patients composed one half to one third of all patients undergoing angioplasty, these median values are consistent with an overall physician volume of 26 to 39 cases per year and an overall hospital volume of 196 to 294 cases per year. After adjusting for age, sex, race, acute myocardial infarction, and comorbidity, low-volume physicians were associated with higher rates of bypass surgery (
P
<.001) and low-volume hospitals were associated with higher rates of bypass surgery and death (
P
<.001). Improving outcomes were seen up to threshold values of 75 Medicare cases per physician and 200 Medicare cases per hospital.

Conclusions
More than 50% of physicians and 25% of hospitals performing coronary angioplasty in 1992 were unlikely to have met the minimum volume guidelines first published in 1988, and these patients had worse outcomes. While more recent data are required to determine whether the same relationships persist after the introduction of newer technologies, this study suggests that adherence to minimum volume standards by physicians and hospitals will lead to better outcomes for elderly patients undergoing coronary angioplasty.
Development and Prospective Validation of a Clinical Index to Predict Survival in Ambulatory Patients Referred for Cardiac Transplant Evaluation
Authors: Aaronson Keith D. , Schwartz J. Sanford , Chen Tze-Ming , Wong Kar-Lai , Goin James E. , Mancini Donna M.
Published: June 2012

Background
Risk stratification of patients with end-stage congestive heart failure is a critical component of the transplant candidate selection process. Accurate identification of individuals most likely to survive without a transplant would facilitate more efficient use of scarce donor organs.

Methods and Results
Multivariable proportional hazards survival models were developed with the use of data on 80 clinical characteristics from 268 ambulatory patients with advanced heart failure (derivation sample). Invasive and noninvasive models (with and without catheterization-derived data) were constructed. A prognostic score was determined for each patient from each model. Stratum-specific likelihood ratios were used to develop three prognostic-score risk groups. The models were prospectively validated on 199 similar patients (validation sample) by calculation of the area under the receiver operating characteristic curve for 1-year event-free survival, the censored c-index for event-free survival, and comparison of event-free survival curves for prognostic-score risk strata. Outcome events were defined as urgent transplant or death without transplant. The noninvasive model performed well in both samples, and increased performance was not attained by the addition of catheterization-derived variables. Prognostic-score risk groups derived from the noninvasive model in the derivation sample effectively stratified the risk of an outcome event in both samples (1-year event-free survival for derivation and validation samples, respectively: low risk, 93% and 88%; medium risk, 72% and 60%; high risk, 43% and 35%).

Conclusions
Selection of candidates for cardiac transplantation may be improved by use of this noninvasive risk-stratification model.
Elective Stenting of the Extracranial Carotid Arteries
Authors: Yadav Jay S. , Roubin Gary S. , Iyer Sriram , Vitek Jiri , King Peter , Jordan William D. , Fisher Winfield S.
Published: June 2012

Background
Surgical endarterectomy has been shown to be superior to medical management in the management of severe carotid stenosis in both symptomatic and asymptomatic patients. Endarterectomy, although effective, does have limitations, and percutaneous techniques may offer an alternative method of treatment.

Methods and Results
The feasibility and safety of percutaneous carotid angioplasty and elective (primary) stenting was evaluated prospectively in a consecutive series of 107 patients. One hundred twenty-six carotid arteries with significant stenosis were treated. This series represented a high-risk subset that included patients with previous ipsilateral endarterectomy and severe medical comorbidity. Forty-five percent of the patients were referred by surgeons. Patients had independent neurological examinations before and after the procedure and follow-up cerebral angiography at 6 months. The mean (±SD) stenosis was reduced from 78±14% to 2±5%. There were 7 minor strokes, 2 major strokes, and 1 death during the initial hospitalization and first 30 days after the procedure. For the combined end point of all strokes and death, the incidence was 7.9%. For ipsilateral major stroke and death, the incidence was 1.6%. There were no strokes during the follow-up period. Mean angiographic stenosis at 6 months in 81 patients was 18±16% (range, −21% to 57%). Four (4.9%) of these 81 patients had asymptomatic restenosis. Five asymptomatic patients had repeat intervention: 2 had angioplasty for restenosis, 2 had angioplasty for stent deformation, and 1 had endarterectomy for restenosis.

Conclusions
In a high-risk group of patients, percutaneous carotid angioplasty and stenting are feasible and can be performed with low restenosis and repeat intervention rates.
l
-Arginine Prevents Xanthoma Development and Inhibits Atherosclerosis in LDL Receptor Knockout Mice
Authors: Aji Walif , Ravalli Stefano , Szabolcs Matthias , Jiang Xian-cheng , Sciacca Robert R. , Michler Robert E. , Cannon Paul J.
Published: June 2012

Background
The potential antiatherosclerotic actions of NO were investigated in four groups of mice (n=10 per group) lacking functional LDL receptor genes, an animal model of familial hypercholesterolemia. Group 1 was fed a regular chow diet. Groups 2 through 4 were fed a 1.25% high-cholesterol diet. In addition, group 3 received supplemental
l
-arginine and group 4 received
l
-arginine and
N
ω
-nitro-
l
-arginine (L-NA), an inhibitor of NO synthase (NOS).

Methods and Results
Animals were killed at 6 months; aortas were stained with oil red O for planimetry and with antibodies against constitutive and inducible NOSs. Plasma cholesterol was markedly increased in the animals receiving the high-cholesterol diet. Xanthomas appeared in all mice fed the high-cholesterol diet alone but not in those receiving
l
-arginine. Aortic atherosclerosis was present in all mice on the high-cholesterol diet. The mean atherosclerotic lesion area was reduced significantly (
P
<.01) in the cholesterol-fed mice given
l
-arginine compared with those receiving the high-cholesterol diet alone. The mean atherosclerotic lesion area was significantly larger (
P
<.01) in cholesterol-fed mice receiving
l
-arginine + L-NA than in those on the high-cholesterol diet alone. Within the atherosclerotic plaques, endothelial cells immunoreacted for endothelial cell NOS; macrophages, foam cells, and smooth muscle cells immunostained strongly for inducible NOS and nitrotyrosine residues.

Conclusions
The data indicate that
l
-arginine prevents xanthoma formation and reduces atherosclerosis in LDL receptor knockout mice fed a high-cholesterol diet. The abrogation of the beneficial effects of
l
-arginine by L-NA suggests that the antiatherosclerotic actions of
l
-arginine are mediated by NOS. The data suggest that
l
-arginine may be beneficial in familial hypercholesterolemia.
Recombinant Staphylokinase Variants With Altered Immunoreactivity
Authors: Collen De´sire´ , Stockx Luc , Lacroix Henri , Suy Raphael , Vanderschueren Steven
Published: June 2012

Background
The thrombolytic potency and antibody induction of selected variants of recombinant staphylokinase (SakSTAR), including SakSTAR(K
74
) with Lys74, SakSTAR(E
75
) with Glu75, SakSTAR(EER) with Glu38, Glu75, and Arg77, and SakSTAR(K
74
ER) with Lys74, Glu75, and Arg77 replaced by Ala, were studied.

Methods and Results
In rabbits, SakSTAR(K
74
) and SakSTAR(EER) elicited significantly less circulating neutralizing activity than SakSTAR and SakSTAR(E
75
) (
P
=.005 and
P
=.0002 versus SakSTAR, respectively). In baboons, SakSTAR(K
74
) induced significantly fewer antibodies than wild-type SakSTAR (
P
<.05). Intra-arterial administration in patients with peripheral arterial occlusion of SakSTAR(K
74
) (n=11) or SakSTAR(K
74
ER) (n=6) induced significantly fewer circulating neutralizing antibodies [median values and interquartile ranges, 20 (3.8 to 26) and 2.4 (0.2 to 59) μg compound neutralized/mL plasma after 3 to 4 weeks (
P
=.01 and
P
=.035 versus SakSTAR, respectively)] than SakSTAR (n=9) [median value and interquartile range, 93 (24 to 110) μg compound neutralized/mL plasma]. Overt neutralizing antibody induction (>10 μg compound neutralized/mL plasma) occurred in all 9 patients given wild-type SakSTAR, in 6 of the 11 SakSTAR(K
74
) patients (
P
=.038 versus SakSTAR), and in 2 of the 6 SakSTAR(K
74
ER) patients (
P
=.011 versus SakSTAR).

Conclusions
SakSTAR(K
74
), a variant of recombinant staphylokinase with a single substitution of Lys74 with Ala, and SakSTAR(K
74
ER), with Lys74, Glu75, and Arg77 substituted with Ala, have intact thrombolytic potencies but induce significantly less antibody formation in patients.
Prevention of Bioprosthetic Heart Valve Calcification by Ethanol Preincubation
Authors: Vyavahare Narendra , Hirsch Danielle , Lerner Eyal , Baskin Jonathan Z. , Schoen Frederick J. , Bianco Richard , Kruth Howard S. , Zand Robert , Levy Robert J.
Published: June 2012

Background
Calcification of the cusps of bioprosthetic heart valves fabricated from either glutaraldehyde cross-linked porcine aortic valves or bovine pericardium frequently causes the clinical failure of these devices. Our investigations studied ethanol pretreatment of glutaraldehyde cross-linked porcine aortic valves as a new approach to prevent cuspal calcification. The hypothesis governing this approach holds that ethanol pretreatment inhibits calcification resulting from protein structural alterations and lipid extraction.

Methods and Results
Results demonstrated complete inhibition of calcification of glutaraldehyde-pretreated porcine bioprosthetic aortic valve cusps by 80.0% ethanol in rat subdermal implants (60-day ethanol-pretreated calcium level, 1.87±0.29 μg/mg tissue compared with control calcium level, 236.00±6.10 μg/mg tissue) and in sheep mitral valve replacements (ethanol-pretreated calcium level, 5.22±2.94 μg/mg tissue; control calcium level, 32.50±11.50 μg/mg tissue). The mechanism of ethanol inhibition may be explained by several observations: ethanol pretreatment resulted in an irreversible alteration in the amide I band noted in the infrared spectra for both purified type I collagen and glutaraldehyde cross-linked porcine aortic leaflets. Ethanol pretreatment also resulted in nearly complete extraction of leaflet cholesterol and phospholipid.

Conclusions
Ethanol pretreatment of glutaraldehyde cross-linked porcine aortic valve bioprostheses represents a highly efficacious and mechanistically based approach and may prevent calcific bioprosthetic heart valve failure.
Nitric Oxide Contributes to the Progression of Myocardial Damage in Experimental Autoimmune Myocarditis in Rats
Authors: Ishiyama Shigeru , Hiroe Michiaki , Nishikawa Toshio , Abe Shinji , Shimojo Takashi , Ito Hiroshi , Ozasa Sakae , Yamakawa Katsutoshi , Matsuzaki Masunori , Mohammed Minhaz Uddin , Nakazawa Hiroe , Kasajima Takeshi , Marumo Fumiaki
Published: June 2012

Background
Excess amounts of NO produced by an inducible NO synthase (iNOS) in response to cytokines may be cytotoxic and can be destructive to tissue. We investigated the role of NO in the development of myocardial damage and the effects of aminoguanidine (AG), an inhibitor of iNOS, on experimental autoimmune myocarditis in rats.

Methods and Results
Autoimmune myocarditis was induced in 20 Lewis rats by injection of porcine cardiac myosin. Ten of the 20 rats were administered AG. The severity of myocarditis was evaluated by measuring the size of myocarditic lesion and serum levels of CK-MB. Serum NO levels were determined using the Cd/Cu method. Tissue specimens were immunohistochemically examined for iNOS and nitrotyrosine. Histopathological study revealed extensive myocardial destruction and massive inflammatory cell infiltration in AG-untreated rats but only focal mononuclear cell infiltration in AG-treated rats. The mean percent areas of inflammatory lesions in the untreated and treated rats were 56±13% and 3±2%, respectively (
P
<.001). NO levels were 102±23 and 25±9 IU/L, respectively (
P
<.01). CK-MB levels were 68±13 and 16±13 nmol/L, respectively (
P
<.01). Superoxide production as measured with an ex vivo monitoring system was also significantly decreased in the treated rats. Nitrotyrosine relating to the generation of peroxynitrite was detected through immunostaining in the inflammatory lesions of untreated rats but not in those of treated rats.

Conclusions
Excess amounts of NO produced by iNOS appear to contribute to the progression of myocardial damage in myocarditis. AG may prove to be useful in the treatment of myocarditis.
Coronary Microcirculation in Health and Disease
Authors: Chilian William M.
Published: June 2012

Abstract
This article summarizes a 2-day workshop on the coronary microcirculation held in Bethesda, Md, in September 1994 and sponsored by the National Heart, Lung, and Blood Institute of the National Institutes of Health. The workshop explored a variety of topics pertaining to coronary microvascular physiology and pathophysiology. The latest methodologies that are being used to investigate the coronary microvasculature, including endoscopic microscopy of the intramural coronary microvasculature and micro–x-ray computerized tomography, were discussed. The most recent advances in the regulation of the coronary microcirculation—for example, myogenic and flow-dependent responses, K
ATP
channels, and regional heterogeneity—were reported. The workshop touched on the relation of the microcirculation to clinically important conditions and offered recommendations for future research in this important area. Comparisons are made to recent advances in the peripheral circulation and current gaps in our knowledge concerning the coronary microcirculation. In recent years, research on the coronary microcirculation has made substantial advances, in part as a result of investigations in the peripheral microcirculation but also because of the application of unique methodologies. This research is providing new ways to investigate abnormalities of myocardial perfusion, an area of inquiry that until recently has been limited to examination of coronary pressure-flow relationships.
Hyperreactivity to Nitrovasodilators in Forearm Vasculature Is Related to Autonomic Dysfunction in Insulin-Dependent Diabetes Mellitus
Authors: Ma¨kimattila Sari , Ma¨ntysaari Matti , Groop Per-Henrik , Summanen Paula , Virkama¨ki Antti , Schlenzka Anna , Fagerudd Johan , Yki-Ja¨rvinen Hannele
Published: June 2012

Background
The link between diabetes and vascular disease is poorly understood. Data regarding endothelial function in vivo in patients with insulin-dependent diabetes mellitus (IDDM) have been inconsistent with in vitro studies demonstrating hyperglycemia-induced impairments in endothelium-dependent vasodilation.

Methods and Results
We determined whether alterations in neural control of the vascular tone might contribute to blood flow responses to intrabrachial infusions of acetylcholine (ACh), sodium nitroprusside (SNP), and
l
-
N
-monomethyl-arginine (L-NMMA) in 22 men with IDDM (12 with normoalbuminuria, HbA
1c
=8.6±0.3%; 10 with macroalbuminuria, HbA
1c
=8.6±0.3%) and 11 matched normal men. Autonomic function was assessed from reflex vasoconstriction to cold, the blood pressure response to standing and hand grip, and heart rate variation, including spectral analysis, during controlled breathing, and the Valsalva maneuver. IDDM with macroalbuminuria exhibited hyperresponsiveness to both ACh and SNP compared with the patients with normoalbuminuria or normal subjects. Reflex sympathetic vasoconstriction to cold was severely impaired in the IDDM patients with macroalbuminuria (−19±6%) compared with normoalbuminuric patients (−39±5%,
P
<.05) and normal subjects (−54±7%,
P
<.001). The macroalbuminuric patients also had evidence of autonomic dysfunction during controlled and deep breathing tests and during the Valsalva maneuver. Within the group of IDDM patients, neither the urinary albumin excretion rate nor other parameters such as HbA
1c
or serum cholesterol correlated with forearm blood flow during the vasoactive drug infusions. There were, however, significant inverse correlations between several measures of both sympathetic and parasympathetic autonomic functions and vascular hyperresponsiveness to SNP and ACh. For example, the Valsalva ratio was inversely correlated with the increase in blood flow in response to infusion of 3 (
r
=−.74,
P
<.001) and 10 (
r
=−.73,
P
<.001) μg/min SNP and 7.5 (
r
=−.73,
P
<.001) and 15 (
r
=−.75,
P
<.001) μg/min ACh.

Conclusions
These data are consistent with idea that altered neurotransmission is an important determinant of vascular reactivity of diabetic blood vessels to nitrovasodilators in vivo.
Dobutamine Echocardiography and Quantitative Rest-Redistribution
201
Tl Tomography in Myocardial Hibernation
Authors: Qureshi Usman , Nagueh Sherif F. , Afridi Imran , Vaduganathan Periyanan , Blaustein Alvin , Verani Mario S. , Winters William L. , Zoghbi William A.
Published: June 2012

Background
The purposes of this study were to evaluate the comparative accuracy of dobutamine echocardiography and quantitative rest-redistribution
201
Tl tomography in the prediction of recovery of function after revascularization and to assess the relation of contractile reserve to thallium uptake.

Methods and Results
Thirty-four patients with stable coronary disease and regional dysfunction underwent dobutamine echocardiography (2.5 up to 40 μg·kg
−1
·min
−1
) and rest-redistribution
201
Tl tomography 1 day before revascularization. Resting echocardiography and scintigraphy were repeated at ≥6 weeks. Before revascularization, resting
201
Tl uptake was similar in segments demonstrating biphasic or sustained improvement and was higher than in those exhibiting no change or worsening function during dobutamine. After revascularization,
201
Tl uptake increased only in segments that showed a biphasic response (from 66±12% to 78±13%;
P
<.05). Biphasic response had a sensitivity of 74% and specificity of 89% for prediction of recovery. The use of biphasic or sustained improvement responses increased the sensitivity to 86% with a decrease in specificity to 68%. Qualitative thallium assessment provided a high sensitivity (98%) but poor specificity (27%). Quantification of thallium uptake, however, improved its accuracy: a maximal uptake (at rest or redistribution) of ≥60% yielded a 90% sensitivity and a 56% specificity.

Conclusions
In patients with myocardial hibernation, biphasic response during dobutamine is less sensitive but more specific for recovery of function, whereas indexes of
201
Tl scintigraphy are in general more sensitive and less specific, the least accurate being a qualitative assessment of thallium uptake. The sensitivity and specificity of both methods, however, can be altered depending on the quantitative criteria of thallium uptake or combination of responses of the myocardium to dobutamine.
Increased Airway Pressure and Simulated Branch Pulmonary Artery Stenosis Increase Pulmonary Regurgitation After Repair of Tetralogy of Fallot
Authors: Chaturvedi Rajiv R. , Kilner Philip J. , White Paul A. , Bishop Andrew , Szwarc Richard , Redington Andrew N.
Published: June 2012

Background
Pulmonary regurgitation (PR) is an important determinant of outcome after repair of tetralogy of Fallot. Baseline PR was measured by magnetic resonance (MR) phase velocity mapping and from real-time right ventricular pressure-volume loops with a conductance catheter. Subsequently, the impact of two loading maneuvers (increased airway pressure, simulated branch pulmonary artery stenosis) on PR was assessed by the conductance catheter method.

Methods and Results
Thirteen patients, 3 to 35 years after tetralogy of Fallot repair or pulmonary valvotomy, had PR measured by MR phase velocity mapping while breathing spontaneously. During catheterization under general anesthesia, PR was estimated from right ventricular pressure-volume loops generated by conductance and microtip pressure catheters. The effect of increased airway pressure (continuous positive airway pressure, 20 cm H
2
O; n=12) and simulated branch pulmonary artery stenosis (transient balloon occlusion of a branch pulmonary artery, n=7) was measured. Basal PR fraction derived by MR and from right ventricular pressure-volume loops had a correlation coefficient of .76 and mean of differences of 2.0±18.2% (95% limits of agreement). Increased airway pressure increased PR (16.3±11.4% to 25.7±17.3%,
P
<.01). Simulated branch pulmonary artery stenosis increased right ventricular end-systolic pressure (69.1±21.4 to 78.7±23.1 mm Hg,
P
<.05) and PR (27.5±11.3% to 36.9±12.8%,
P
<.05).

Conclusions
There was reasonable agreement between MR phase velocity–derived PR fraction and that obtained from right ventricular pressure-volume loops generated by use of conductance and pressure-microtip catheters. Exacerbation of PR by increased airway pressure and branch pulmonary stenosis may be relevant to the acute postoperative and long-term management, respectively, of patients after repair of tetralogy of Fallot.
Low-Molecular-Weight Tumor Necrosis Factor Receptor p55 Controls Induction of Autoimmune Heart Disease
Authors: Bachmaier Kurt , Pummerer Christian , Kozieradzki Ivona , Pfeffer Klaus , Mak Tak W. , Neu Nikolaus , Penninger Josef M.
Published: June 2012

Background
Tumor necrosis factor-α (TNF-α) is involved in the pathogenesis of myocarditis and can bind to either tumor necrosis factor receptor (TNF-R) p55 or TNF-Rp75. However, it is not known which TNF-R mediates the specific functions of TNF in disease. To determine the role of the TNF/TNF-R system in chronic heart disease, we used a murine model of cardiac myosin–induced myocarditis that closely resembles the chronic stages of virus-induced myocarditis in humans.

Methods and Results
Mice lacking TNF-Rp55 expression after targeted disruption of the TNF-Rp55 gene were backcrossed into a genetic background susceptible to the induction of myocarditis with cardiac myosin. Here, we demonstrate that TNF-Rp55 gene–deficient mice did not develop any inflammatory infiltration into the heart after autoantigen injection, whereas control littermates showed autoimmune myocarditis at high prevalence and severity. Despite the absence of autoimmune heart disease, TNF-Rp55
−/−
mice produced cardiac myosin–specific IgG autoantibodies, indicating that activation of autoaggressive T and B lymphocytes had occurred. However, heart interstitial cells failed to express major histocompatibility complex (MHC) class II molecules in TNF-Rp55
−/−
animals, and adoptive transfer of autoreactive T cells resulted in heart disease only in TNF-Rp55
+/+
but not in TNF-Rp55
−/−
littermates.

Conclusions
Cardiac myosin–induced myocarditis is dependent on autoaggressive T cells and on autoantigen presentation in association with MHC class II molecules within the heart. Thus, lack of TNF-Rp55 expression could interfere with either lymphocyte activation or target organ susceptibility. The data presented here show that the TNF-Rp55 is a key regulator for the induction of autoimmune heart disease by its controlling target organ susceptibility.
Effects of MCI-154, a Calcium Sensitizer, on Left Ventricular Systolic and Diastolic Function in Pacing-Induced Heart Failure in the Dog
Authors: Teramura Shinobu , Yamakado Tetsu , Maeda Mitsugu , Nakano Takeshi
Published: June 2012

Background
MCI-154 is a positive inotropic agent that increases the myofilament response to Ca
2+
. Whether MCI-154 has beneficial effects on left ventricular dysfunction in chronic heart failure is not known. We examined the effects of MCI-154 on left ventricular systolic and diastolic function in pacing-induced heart failure in dogs.

Methods and Results
We studied eight anesthetized dogs before and 2 to 4 weeks after rapid right ventricular pacing. Left cineventriculograms with simultaneous left ventricular pressures (tip manometer) were obtained before and during intravenous administration of MCI-154 (1.0 μg·kg
−1
·min
−1
for 15 minutes) in the control and heart-failure states. Left ventricular volume dynamics was derived from frame-by-frame (20-ms) analyses of left ventricular angiograms. In heart failure, left ventricular contractility as assessed by shifts of the end-systolic pressure-volume ratio, evaluated by inferior vena cava occlusion, was improved by MCI-154 (+1.94 mm Hg/mL,
P
<.05) to an extent similar to that in the control state (+2.47 mm Hg/mL,
P
<.05). MCI-154 also accelerated left ventricular relaxation, assessed by the time constant of isovolumic pressure decay (T
1/2
), in both states. The absolute decrease in T
1/2
with MCI-154 in heart failure was significantly greater than in the control state (−8.2 versus −3.1 ms,
P
<.05). In heart failure, MCI-154 shifted the left ventricular diastolic pressure-volume relation clearly downward, suggesting increased diastolic distensibility.

Conclusions
MCI-154 improved not only left ventricular systolic function but also diastolic relaxation and distensibility in a chronic heart failure model.
Hypertension Increases Connexin43 in a Tissue-Specific Manner
Authors: Haefliger Jacques-Antoine , Castillo Einar , Waeber Ge´rard , Bergonzelli Gabriela E. , Aubert Jean-Franc¸ois , Sutter Esther , Nicod Pascal , Waeber Bernard , Meda Paolo
Published: June 2012

Background
Connexin43 (Cx43), a membrane protein involved in the control of cell-to-cell communication, is thought to play a role in the contractility of the vascular wall and in the electrical coupling of cardiac myocytes. The aim of this study was to investigate the effects of experimental hypertension on Cx43 expression in rat aorta and heart.

Methods and Results
Rats were made hypertensive after one renal artery was clipped (two kidney, one-clip renal model) or after the administration of deoxycorticosterone and salt (DOCA-salt model). After 4 weeks, all rats showed a similar increase in intra-arterial mean blood pressure and in the thickness of both the aortic wall and the heart. Northern blot analysis of aorta mRNA and immunolabeling for Cx43 showed that hypertensive rats expressed twice as much Cx43 in aorta as the control animals. In contrast, no difference in Cx43 mRNA or in the immunolabeled protein was observed in heart.

Conclusions
The results show that rats exhibiting a similar degree of blood pressure elevation, as the result of different mechanisms, feature a comparable increase in
Cx43
gene expression, which was observed in the aortic but not in the cardiac muscle. These data suggest that localized mechanical forces induced by hypertension are major tissue-specific regulators of Cx43 expression.
Rapid and Simple Platelet Function Assay to Assess Glycoprotein IIb/IIIa Receptor Blockade
Authors: Coller Barry S. , Lang Daniel , Scudder Lesley E.
Published: June 2012

Background
The platelet glycoprotein (GP) IIb/IIIa receptor antagonist c7E3 Fab (abciximab; ReoPro) has been approved as an antithrombotic agent, and other GP IIb/IIIa antagonists, including oral agents, are under development. At present, there are no rapid and simple assays to monitor GP IIb/IIIa receptor blockade.

Methods and Results
An assay was devised based on the ability of platelets in whole blood to rapidly agglutinate fibrinogen-coated beads when stimulated with a peptide, (iso-S)FLLRN, that activates a platelet thrombin receptor but resists inactivation by plasma aminopeptidase M. Preincubation of normal blood with increasing concentrations of c7E3 Fab led to increasing inhibition of the assay, correlating with increased GP IIb/IIIa receptor blockade. Assay conditions were chosen so that agglutination was inhibited at 2 minutes when >82% of the receptors were blocked. Similar results were obtained with the use of GP IIb/IIIa antagonists based on the arginine-glycine-aspartic acid (RGD) cell-recognition sequence.

Conclusions
A simple and rapid assay sensitive to GP IIb/IIIa receptor blockade has been developed that may be helpful in optimizing GP IIb/IIIa antagonist therapy.
Platelet Activation by Superoxide Anion and Hydroxyl Radicals Intrinsically Generated by Platelets That Had Undergone Anoxia and Then Reoxygenated
Authors: Leo Roberto , Pratico` Domenico , Iuliano Luigi , Pulcinelli Fabio M. , Ghiselli Andrea , Pignatelli Pasquale , Colavita Angela R. , FitzGerald Garret A. , Violi Francesco
Published: June 2012

Background
Platelet activation has been demonstrated in experimental and clinical models of ischemia-reperfusion, but the underlying mechanism is still unclear. We mimicked the ischemia-reperfusion model in vitro by exposing platelets to anoxia-reoxygenation (A-R) and evaluated the role of oxygen free radicals (OFRs), which are usually produced during the reperfusion phase, in inducing platelet activation.

Methods and Results
Human platelets were exposed to 15 and 30 minutes of anoxia and then reoxygenated. Compared with control platelets kept in atmospheric conditions, platelets exposed to A-R showed spontaneous platelet aggregation (SPA), which was maximal after 30 minutes of anoxia. Superoxide dismutase (SOD) (–74%,
P
<.005), catalase (–67%,
P
<.005), SOD plus catalase (–82%,
P
<.005), and the hydroxyl radical (OH°) scavengers mannitol (–66%,
P
<.005) and deoxyribose (–55%,
P
<.005) inhibited SPA. Platelets that had undergone A-R released superoxide anion (O
2
–
), as detected by lucigenin chemiluminescence. Also, platelets exposed to A-R and incubated with salicylic acid generated 2,3- and 2,5-dihydroxybenzoates, which derive from salicylic acid reaction with OH°. SPA was significantly inhibited by the cyclooxygenase enzyme inhibitors aspirin and indomethacin; by SQ29548, a thromboxane (Tx) A
2
receptor antagonist; by diphenyliodonium, an inhibitor of flavoprotein-dependent enzymes; and by arachidonyl trifluoromethyl ketone, a selective inhibitor of cytosolic phospholipase A
2
. Platelets exposed to A-R markedly generated inositol 1,3,4-trisphosphate and TxA
2
, which were inhibited by incubation of platelets with SOD plus catalase.

Conclusions
This study shows that platelets exposed to A-R intrinsically generated O
2
–
and OH°, which in turn activate arachidonic acid metabolism via phospholipases A
2
and C, and provides further support for the use of antioxidant agents as inhibitors of platelet function in ischemia-reperfusion models.
Angina Pectoris in Patients With Aortic Stenosis and Normal Coronary Arteries
Authors: Julius Barbara K. , Spillmann Martin , Vassalli Giuseppe , Villari Bruno , Eberli Franz R. , Hess Otto M.
Published: June 2012

Background
The incidence of angina pectoris (AP) in patients with severe aortic stenosis (AS) and normal coronary arteries has been reported to be 30% to 40%. The exact pathophysiological mechanism, however, is not known. The purpose of this work was to evaluate the various hemodynamic and angiographic determinants of myocardial perfusion in 61 patients with severe AS.

Methods and Results
In a retrospective analysis, 61 patients with severe AS and without significant coronary artery disease were studied. Thirty-three patients with atypical chest pain and angiographically normal arteries served as control subjects. Patients were divided into two groups: 32 with AP and 29 without AP. Quantitative coronary angiography was performed in 59 patients and 22 control subjects. Coronary flow reserve was determined in 29 patients and 7 control subjects by use of coronary sinus thermodilution technique. Patients with AP had a lower left ventricular (LV) muscle mass, an increased LV peak systolic pressure, and increased wall stress than those without AP. Vessels of the left coronary artery were smaller and coronary flow reserve was lower in patients with AP than in those without. Inadequate LV hypertrophy with an increased wall stress was found in patients with AP but not in patients without AP.

Conclusions
Myocardial ischemia in patients with severe AS can occur in the absence of coronary artery disease and appears to be due to inadequate LV hypertrophy with high systolic and diastolic wall stresses and a reduced coronary flow reserve. The cause of inadequate LV hypertrophy, however, remains unclear.
Prevalence of Thrombus, Spontaneous Echo Contrast, and Atrial Stunning in Patients Undergoing Cardioversion of Atrial Flutter
Authors: Irani Waleed N. , Grayburn Paul A. , Afridi Imran
Published: June 2012

Background
Several studies have shown that patients undergoing cardioversion of atrial fibrillation have a high prevalence of of atrial thrombus and spontaneous echo contrast and frequently develop atrial stunning after restoration of sinus rhythm. These findings are strongly associated with increased risk of embolism in these patients. However, little is known about the prevalence of these markers of thromboembolism in patients undergoing cardioversion of atrial flutter.

Methods and Results
We performed transesophageal echocardiography in 47 consecutive, nonanticoagulated patients scheduled for elective cardioversion of atrial flutter. In patients who underwent successful cardioversion, mitral inflow velocity was recorded by transthoracic pulsed Doppler examination immediately after restoration of sinus rhythm. All patients were men (mean age, 65±10 years). Mean duration of flutter was 4±9 weeks. Atrial thrombus and/or spontaneous echo contrast were found in 16 patients (34%). Left atrial thrombus was seen in 5 patients (11%), either with (n=4) or without spontaneous contrast. Of 40 patients with successful cardioversion, atrial mechanical activity was absent in 28% immediately after restoration of sinus rhythm.

Conclusions
Our findings suggest that contrary to traditional teaching, atrial thrombus and spontaneous contrast are not uncommon in patients with atrial flutter and cardioversion may be associated with increased risk of thromboembolism.
Disturbed Connexin43 Gap Junction Distribution Correlates With the Location of Reentrant Circuits in the Epicardial Border Zone of Healing Canine Infarcts That Cause Ventricular Tachycardia
Authors: Peters Nicholas S. , Coromilas James , Severs Nicholas J. , Wit Andrew L.
Published: June 2012

Background
Slow, nonuniform conduction caused by abnormal gap-junctional coupling of infarct-related myocardium is thought to be a component of the arrhythmogenic substrate. The hypothesis that changes in gap-junctional distribution in the epicardial border zone (EBZ) of healing canine infarcts define the locations of reentrant ventricular tachycardia (VT) circuits was tested by correlating activation maps of the surviving subepicardial myocardial layer with immunolocalization of the principal gap-junctional protein, connexin43 (Cx43).

Methods and Results
The EBZ overlying 4-day-old anterior infarcts in three dogs with inducible VT and three noninducible dogs was mapped with a high-resolution electrode array and systematically examined by standard histology and confocal immunolocalization of Cx43. The thickness of the EBZ was significantly less in the hearts with (538±257 μm) than without (840±132 μm;
P
<.05) VT. At the interface with the underlying necrotic cells, the EBZ myocardium showed a marked disruption of gap-junctional distribution, with Cx43 labeling abnormally arrayed longitudinally along the lateral surfaces of the cells. In the EBZ of all hearts, the disrupted Cx43 labeling extended part of the way to the epicardial surface, with the most superficial epicardial myocytes having the normal transversely orientated pattern. Only in the hearts with inducible VT did the disorganization extend through the full thickness of the surviving layer at sites correlating with the location of the central common pathways of the figure-of-8 reentrant VT circuits.

Conclusions
Altered gap-junctional distribution is part of the early remodeling of myocardium after infarction, and by defining the location of the common central pathway of the reentrant VT circuits, it may be a determinant of VT susceptibility.
Origin of Extracellular Matrix Synthesis During Coronary Repair
Authors: Shi Yi , O'Brien James E. , Ala-Kokko Leena , Chung Wooksung , Mannion John D. , Zalewski Andrew
Published: June 2012

Background
Coronary injury triggers differentiation of activated adventitial fibroblasts to myofibroblasts, which may contribute to neointimal formation and vascular remodeling. Accordingly, the purpose of this study was to examine the cellular origin of the enhanced synthesis of extracellular matrix proteins during coronary repair.

Methods and Results
The time course and localization of collagen and elastin expression were examined by in situ hybridization and immunohistochemistry in porcine coronary arteries after balloon-induced injury. Procollagen-α
1
(I) transcripts and intracellular type I procollagen protein increased in the adventitia within 2 days after injury. This was followed by a sustained synthesis of type I procollagen in neointima beginning at 7 days and the extracellular accumulation of type I collagen in both layers. The origin of synthetic cells was further examined by colocalization of type I procollagen and bromodeoxyuridine labeling to activated adventitial cells, which translocated to neointima. Neointimal cells exhibited sustained synthetic activity manifested by the presence of type I procollagen and elastin at 3 months after injury. In contrast, the media showed only minor changes in the synthesis of collagen or elastin throughout coronary repair.

Conclusions
Activated adventitial fibroblasts are endowed with synthetic capabilities after coronary injury. They express type I procollagen, with some of them translocating to the intima, where they continue to synthesize procollagen. The accumulation of type I collagen is evident in the adventitia and neointima, whereas elastin accumulates mainly in neointima. These findings support the involvement of adventitial fibroblasts in coronary repair and remodeling after endoluminal injury.
AT
1
and AT
2
Angiotensin Receptor Gene Expression in Human Heart Failure
Authors: Haywood Guy A. , Gullestad Lars , Katsuya Tomohiro , Hutchinson Howard G. , Pratt Richard E. , Horiuchi Masatsugu , Fowler Michael B.
Published: June 2012

Background
The availability of selective antagonists for angiotensin II receptors has focused interest on the gene expression of angiotensin II–receptor subtypes in the human heart.

Methods and Results
We analyzed expression of the AT
1
and AT
2
subtypes of the angiotensin II receptor in ventricular myocardium taken from 9 donor hearts before implantation and from 12 patients with heart failure (6 with dilated cardiomyopathy and 6 with ischemic heart disease). Competitive reverse transcription–polymerase chain reaction with synthetic RNA internal standards was used to detect mRNA for both subtypes and to quantify relative differences in levels between failing and nonfailing ventricular myocardium. AT
1
- and AT
2
-receptor mRNA could be detected in all samples. AT
1
-receptor gene expression was 2.5-fold greater in nonfailing hearts than in patients with failing hearts (
P
=.015). There was no significant difference in AT
2
-receptor mRNA expression in failing and nonfailing hearts.

Conclusions
The level of expression of the angiotensin AT
1
receptor appears to decrease in the failing human ventricle whereas the level of AT
2
expression is unaffected. These changes parallel the changes found in human ventricular myocardium at the receptor level, suggesting that the changes in receptor level may result from changes in gene expression or mRNA stability.
Loading Manipulations Improve the Prognostic Value of Doppler Evaluation of Mitral Flow in Patients With Chronic Heart Failure
Authors: Pozzoli Massimo , Traversi Egidio , Cioffi Giovanni , Stenner Rachel , Sanarico Maurizio , Tavazzi Luigi
Published: June 2012

Background
Mitral flow velocity patterns (MFVPs) evaluated by Doppler echocardiography are strong predictors of survival in various cardiac diseases. However, MFVPs may change over time according to loading conditions. We performed this prospective study to assess whether changes in MFVP induced by loading manipulations provided additional prognostic information in 173 patients with chronic heart failure.

Methods and Results
Simultaneous Doppler echocardiographic and right-sided hemodynamic recordings were obtained at baseline in all patients, during nitroprusside infusion in the 98 patients who had a baseline restrictive (early-to-late flow velocity ratio >1 and deceleration time ≤130 ms) MFVP, and during passive leg lifting in the 75 patients who had a baseline nonrestrictive MFVP. Patients were categorized, according to changes in MFVP, into four groups: 61 patients with an irreversible restrictive, 37 with a reversible restrictive, 48 patients with a stable nonrestrictive, and 27 patients with an unstable nonrestrictive MFVP. Fifty patients experienced major cardiac events. Cox analysis revealed that MFVP was a strong predictor of events and that the response to loading manipulations improved its prognostic value. Patients with an irreversible restrictive MFVP had a higher event rate (51%) than patients with a reversible restrictive MFVP (19%). Among patients with a baseline nonrestrictive MFVP, those with a stable nonrestrictive MFVP had the lowest event rate (6%), whereas the event rate was 33% in patients with an unstable nonrestrictive MFVP.

Conclusions
In patients with chronic heart failure, MFVPs provide independent prognostic information. Their prognostic value can be further increased by assessment of the changes induced in them by loading manipulations.