bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for Longitudinal and Transverse Fiber Conduction in Human Pulmonary Veins
Authors: Sanchez Javier E. , Plumb Vance J. , Epstein Andrew E. , Kay G. Neal
Published: July 2003

Background—

Segmental ostial ablation of the pulmonary veins (PVs) allows for successful control of paroxysmal atrial fibrillation in many patients. We hypothesized that mapping of the left atrial-PV junction with a 64-electrode basket catheter would allow characterization of conduction patterns that would identify sites where ablation is required to electrically isolate the PV.

Methods and Results—

A 64-electrode basket catheter was used to map the PVs of 50 patients undergoing PV isolation procedures for the treatment of atrial fibrillation. Activation along each spline was classified as reflecting either longitudinal, transverse, or no activation. A longitudinal activation pattern recorded along a spline during sinus rhythm in right-sided PV and during CS pacing in left-sided PV before the delivery of any RF energy application had a sensitivity and specificity for a required ostial ablation site of 83% and 82%, respectively. When longitudinal activation along the spline was present during preablation recordings in both sinus rhythm and CS pacing, the sensitivity and specificity were 92% and 90%, respectively. A longitudinal activation pattern after the first RF application that produced a change in PV activation sequence had a sensitivity and specificity for sites where further ablation was required of 91% and 94%, respectively.

Conclusions—

Mapping of PV activation with a 64-electrode basket catheter allows characterization of conduction patterns that predict requirement for ablation. The presence of a longitudinal activation pattern is a strong predictor of ostial sites where ablative energy is required to electrically isolate the PV.
Long-Term Follow-Up of Aortic Intramural Hematoma
Authors: Evangelista Arturo , Dominguez Rosa , Sebastia Carmen , Salas Armando , Permanyer-Miralda Gaieta , Avegliano Gustavo , Elorz Cristina , Gonzalez-Alujas Teresa , Garcia Del Castillo Herminio , Soler-Soler Jordi
Published: July 2003

Background—

Aortic intramural hematoma (IMH) evolves very dynamically in the short-term to regression, dissection, or aortic rupture. The aim of the present study was to assess the long-term clinical and morphological evolution of medically treated IMH.

Methods and Results—

Fifty of 68 consecutive patients with aortic IMH monitored clinically and by imaging techniques at 3, 6, and 12 months and annually thereafter were prospectively studied. Mean follow-up was 45±31 months. In the first 6 months, total IMH regression was observed in 14 and progression to aortic dissection in 18 patients; in 14 of these, the dissection was localized, and 12 later developed pseudoaneurysm. At the end of follow-up, the IMH had regressed completely without dilatation in 17 patients (34%), progressed to classical dissection in 6 (12%), evolved to fusiform aneurysm in 11 (22%), evolved to saccular aneurysm in 4 (8%), and evolved to pseudoaneurysm in 12 (24%). Evolution to dissection was related to echolucency (
P
<0.02) and to longitudinal extension of IMH (
P
<0.01). Multivariate analysis showed an independent association between regression and smaller maximum aortic diameter and between aneurysm formation and atherosclerotic ulcerated plaque and absence of echolucent areas in IMH.

Conclusions—

The most frequent long-term evolution of IMH is to aortic aneurysm or pseudoaneurysm. Complete regression without changes in aorta size is observed in one third of cases, and progression to classical dissection is less common. A normal aortic diameter in the acute phase is the best predictor of IMH regression without complications, and absence of echolucent areas and atherosclerotic ulcerated plaque are associated with evolution to aortic aneurysm.
Effect of Two Different Bypass Techniques on the Serum Troponin-T Levels in Newborns and Children
Authors: Nagy Zsolt L. , Collins Mike , Sharpe Tracy , Mirsadraee Saeed , Guerrero Rafael R. , Gibbs John , Watterson Kevin G.
Published: July 2003

Background—

Cardiac troponin-T is a sensitive marker of myocardial damage. In a prospective study, the effect of 2 different pH strategies during cardiopulmonary bypass on ischemic myocardial injury and clinical outcome was measured in a pediatric population.

Methods and Results—

One hundred one patients (31 neonates 13.2±8.3 days and 70 children 34.5±44.1 months of age) undergoing open-heart surgery were selected to either α-stat (n=51) or pH-stat (n=50) acid-based management protocol. Serum troponin-T levels were measured before and 30 minutes after bypass and then 4 and 24 hours postoperatively. Surgical procedure, bypass details, inotropic support requirement, and postoperative recovery were recorded. Baseline troponin-T level was higher in neonates than in children (0.18±0.22 versus 0.04±0.05 μg/L,
P
=0.02). Also, a higher baseline level was found in patients with pulmonary hypertension (0.13±0.21 versus 0.04±0.05 μg/L,
P
=0.04). Cyanotic children showed a higher peak troponin-T level (3.76±3.11 versus 1.67±1.33 μg/L,
P
=0.04). Peak troponin levels showed a correlation with the length of circulatory arrest and aortic cross-clamp time. Postoperative levels remained high at 24 hours in patients requiring inotropic support. Peak troponin-T levels were significantly lower in the pH-stat group in patients with pulmonary hypertension (
P
=0.03) and in cases where circulatory arrest (
P
=0.01) or inotropic support (
P
=0.01) was necessary during operation than in those with α-stat technique. Postoperative ventilation time and length of intensive care unit stay were also significantly longer with α-stat than with pH-stat technique (
P
=0.005 and
P
=0.006, respectively).

Conclusions—

Cardiac troponin-T sensitively reflects myocardial damage in children. Our results suggest that pH-stat acid-based management protocol may provide better protection against ischemic myocardial damage than α-stat technique.
RhoA Influences the Nuclear Localization of Extracellular Signal–Regulated Kinases to Modulate p21
Waf/Cip1
Expression
Authors: Zuckerbraun Brian S. , Shapiro Richard A. , Billiar Timothy R. , Tzeng Edith
Published: July 2003

Background—

The 42/44-kD mitogen-activated protein kinases (extracellular signal–regulated kinases, ERKs) regulate smooth muscle cell (SMC) cell-cycle progression and can either promote or inhibit proliferation depending on the activation status of the small GTPase RhoA. RhoA is involved in the regulation of the actin cytoskeleton and converges on multiple signaling pathways. However, the mechanism by which RhoA modulates ERK signaling is not well defined. The purpose of this investigation was to examine whether RhoA regulates ERK downstream signaling and cellular proliferation through its effects on the cytoskeleton and the nuclear localization of ERK.

Methods and Results—

Treatment of SMCs with
Clostridia botulinum
C3 exoenzyme, which inhibits RhoA activation, decreased SMC proliferation to 24±7% of that of controls and increased p21
Waf1/Cip1
transcription and protein levels. These effects of RhoA were reversed by inhibition of ERK phosphorylation. However, inactivation of RhoA did not alter levels of ERK phosphorylation but did increase nuclear localization of phosphorylated ERK. In addition, immunostaining demonstrated that phosphorylated ERK associated with the actin cytoskeleton, which was disrupted by C3 exoenzyme. Leptomycin B, an inhibitor of Crm1 that results in ERK nuclear accumulation, similarly increased p21
Waf1/Cip1
.

Conclusions—

RhoA inhibition increased levels of phosphorylated ERK in the cell nucleus. Inhibition of RhoA or pharmacological inhibition of nuclear export resulted in increased p21
Waf1/Cip1
expression and decreased SMC proliferation, effects that were partially dependent on ERK. RhoA regulation of the actin cytoskeleton may determine ERK subcellular localization and its subsequent effects on SMC proliferation.
Inhibitory Cardiac Transcription Factor, SRF-N, Is Generated by Caspase 3 Cleavage in Human Heart Failure and Attenuated by Ventricular Unloading
Authors: Chang Jiang , Wei Lei , Otani Takayuki , Youker Keith A. , Entman Mark L. , Schwartz Robert J.
Published: July 2003

Background—

Knowledge about molecular mechanisms leading to heart failure is still limited, but reduced gene activities and modest activation of caspase 3 are hallmarks of end-stage heart failure. We postulated that serum response factor (SRF), a central cardiac transcription factor, might be a cleavage target for modest activated caspase 3, and this cleavage of SRF may play a dominant inhibitory role in propelling hearts toward failure.

Methods and Results—

We examined SRF protein levels from cardiac samples taken at the time of transplantation in 13 patients with end-stage heart failure and 7 normal hearts. Full-length SRF was markedly reduced and processed into 55- and 32-kDa subfragments in all failing hearts. SRF was intact in normal samples. In contrast, the hearts of 10 patients with left ventricular assist devices showed minimal SRF fragmentation. Specific antibodies to N- and C-terminal SRF sequences and site-directed mutagenesis revealed 2 alternative caspase 3 cleavage sites, so that 2 fragments were detected of each containing either the N- or C-terminal SRF. Expression of SRF-N, the 32-kDa fragment, in myogenic cells inhibited the transcriptional activity of α-actin gene promoters by 50% to 60%, which suggests that truncated SRF functioned as a dominant-negative transcription factor.

Conclusions—

Caspase 3 activation in heart failure sequentially cleaved SRF and generated a dominant-negative transcription factor, which may explain the depression of cardiac-specific genes. Moreover, caspase 3 activation may be reversible in the failing heart with ventricular unloading.
Resistin Promotes Endothelial Cell Activation
Authors: Verma Subodh , Li Shu-Hong , Wang Chao-Hung , Fedak Paul W.M. , Li Ren-Ke , Weisel Richard D. , Mickle Donald A.G.
Published: July 2003

Background—

Adipocyte-derived hormones may represent a mechanism linking insulin resistance to cardiovascular disease. In the present study, we evaluated the direct effects of resistin, a novel adipocyte-derived hormone, on endothelial activation.

Methods and Results—

Endothelial cells (ECs) were incubated with human recombinant resistin (10 to 100 ng/ML, 24 hours), and endothelin-1 (ET-1) release, ET-1 mRNA expression, and nitric oxide (NO) production were assessed. Transient transfection assays were used to evaluate the effects of resistin on transcription of human ET-1 gene promoter. Furthermore, the effects of resistin on AP-1–mutated ET-1 promoter were evaluated. The effects of resistin on expression of vascular cell adhesion molecule (VCAM-1) and monocyte chemoattractant chemokine (MCP-1) were studied in addition to CD40 receptor, CD40 ligand–induced MCP-1 expression, and tumor necrosis factor receptor–associated factor-3 (TRAF3), an inhibitor of CD40 signaling. Incubation of ECs with resistin resulted in an increase in ET-1 release and ET-1 mRNA expression, with no change in NO production. Whereas treatment with resistin resulted in an increase in ET-1 promoter activity, the AP-1–mutated promoter was inactive after resistin stimulation. Additionally, resistin-treated cells showed increased expression of VCAM-1 and MCP-1, with concomitant reductions in TRAF-3 expression. Resistin did not alter CD40 receptor expression; however, increased CD40 ligand induced MCP-1 production.

Conclusions—

The novel adipokine resistin exerts direct effects to promote EC activation by promoting ET-1 release, in part by inducing ET-1 promoter activity via the AP-1 site. Furthermore, resistin upregulates adhesion molecules and chemokines and downregulates TRAF-3, an inhibitor of CD40 ligand signaling. In this fashion, resistin may be mechanistically linked to cardiovascular disease in the metabolic syndrome.
Peroxisome Proliferator-Activated Receptors
Authors: Schiffrin Ernesto L. , Amiri Farhad , Benkirane Karim , Iglarz Marc , Diep Quy N.
Published: July 2003

Peroxisome proliferator-activated receptors (PPAR) are nuclear receptors acting as transcription factors on numerous target genes after heterodimerization with the retinoid X receptor. PPAR-α and PPAR-γ may be activated by different agonists, although the endogenous ligands are unknown. Although PPAR-α is mainly involved in fatty acid oxidation and expressed in liver, kidney, and skeletal muscle, and PPAR-γ is mainly involved in fat cell differentiation and insulin sensitivity, both are expressed in smooth muscle cells and myocardium, although PPAR-γ are scarce in the latter. Activators of PPAR-α such as fatty acids and fibrates, and PPAR-γ such as thiazolidinediones have been shown to exert antiproliferative effects, antagonize angiotensin II actions in vivo and in vitro, and exert antioxidant actions inhibiting generation of reactive oxygen species and activation of inflammatory mediators on blood vessels and the heart. These agents lowered blood pressure in several models of hypertension and corrected endothelial dysfunction. They exerted anti-inflammatory and antifibrotic actions on blood vessels and the heart. With the development of dual α/γ-PPAR activators, these newer agents may become interesting therapeutic agents for prevention of vascular and cardiac complications of hypertension as well as for preventative therapy in other forms of cardiovascular disease.
Inhibitors of 20-HETE Formation Promote Salt-Sensitive Hypertension in Rats
Authors: Hoagland Kimberly M. , Flasch Averia K. , Roman Richard J.
Published: July 2003

This study examined whether chronic blockade of epoxyeicosatrienoic acids (EETs) and/or 20-hydroxyeicosatetraenoic acid (20-HETE) formation promotes development of salt-sensitive hypertension. Changes in blood pressure, renal cytochrome P450 metabolism of arachidonic acid, and 20-HETE excretion in response to a high salt diet were measured in rats chronically treated with 1-aminobenzotriazole (ABT, 50 mg/kg per day) to block EETs and 20-HETE formation or
N
-hydroxy-
N
′-(4-butyl-2 methylphenyl) formamidine (HET0016, 10 mg/kg per day) that selectively reduces 20-HETE formation. ABT reduced blood pressure in rats fed a low salt (0.4% NaCl) diet, but blood pressure rose by 20 mm Hg after these rats were switched to a high salt (8% NaCl) diet for 10 days. HET0016 had no effect on blood pressure in rats fed a low salt diet; however, blood pressure rose by 18 mm Hg after the rats were fed a high salt diet. 20-HETE formation in kidney homogenates rose by 30% and epoxygenase activity doubled when rats were fed a high salt diet. Chronic treatment with ABT and HET0016 inhibited the renal formation of 20-HETE by ≈90%. Renal epoxygenase activity decreased by 76% in ABT-treated rats and was not significantly altered in rats treated with HET0016. 20-HETE excretion rose from 470±21 to 570±41 ng/d when the rats were switched from the low to the high salt diet. 20-HETE excretion fell by 68% and 85% in rats that were chronically treated with ABT and HET0016. These results suggest that chronic blockade of the formation of 20-HETE promotes the development of salt-sensitive hypertension in rats.
Genome-Wide Multipoint Parametric Linkage Analysis of Pulse Pressure in Large, Extended Utah Pedigrees
Authors: Camp Nicola J. , Hopkins Paul N. , Hasstedt Sandra J. , Coon Hilary , Malhotra Alka , Cawthon Richard M. , Hunt Steven C.
Published: July 2003

High pulse pressure, a measure of arterial aging, is an important predictor of cardiovascular and general mortality. It has been suggested that the genetic etiology of pulse pressure is the same as systolic blood pressure. We performed a genome-wide, multipoint, parametric linkage analysis in 26 large, extended Utah pedigrees to locate genes affecting pulse pressure. Four parametric models were considered, including dominant and recessive modes of inheritance involving genes for high and low pulse pressure. Linkage analysis revealed 11 regions with a logarithm of the odds (LOD) >1.5, including 2 regions attaining genome-wide suggestive evidence for linkage after accounting for multiple tests. Inspecting pedigree-specific multipoint linkage evidence suggested that these 2 regions localized to 15.7 cM on chromosome 8p (LOD=2.89), between markers D8S136 and D8S1477, and 20.0 cM on chromosome 12q (LOD=2.59), between D12S1300 and D12S2070. Both regions were identified better by pulse pressure compared with equivalent analyses with systolic or diastolic blood pressure. Results for pulse pressure overlapped favorably with those of others for related blood pressure phenotypes and support the hypothesis that genes with pleiotropic effects on blood pressure phenotypes do exist, but that the genetic etiologies are not identical. In conclusion, our results suggest that pulse pressure might be of use for identifying genes involved in blood pressure phenotypes and arterial aging.
Role of Angiotensin II and Reactive Oxygen Species in Cyclosporine A–Dependent Hypertension
Authors: Nishiyama Akira , Kobori Hiroyuki , Fukui Toshiki , Zhang Guo-Xing , Yao Li , Rahman Matlubur , Hitomi Hirofumi , Kiyomoto Hideyasu , Shokoji Takatomi , Kimura Shoji , Kohno Masakazu , Abe Youichi
Published: July 2003

Treatment with cyclosporine A (CysA), a potent immunosuppressive agent, is associated with systemic and renal vasoconstriction, leading to hypertension. The present study was conducted to elucidate the contribution of angiotensin II (Ang II) to CysA-induced hypertension and reactive oxygen species (ROS) generation. CysA (30 mg/kg per day SC), given for 3 weeks in rats, increased systolic blood pressure (SBP) from 119±2 to 145±3 mm Hg (n=7). Plasma and kidney Ang II levels were significantly higher in CysA-treated rats (136±10 fmol/mL and 516±70 fmol/g) than in vehicle-treated (1 mL olive oil) rats (76±10 fmol/mL and 222±21 fmol/g, n=7). CysA treatment increased AT
1
receptor protein expression in the aorta (by 251±35%), whereas it was reduced in the kidney (by −32±4%). Superoxide anion production in aortic segments and kidney thiobarbituric acid–reactive substance (TBARS) contents were higher in CysA-treated rats (26±2 counts/min per milligram and 37±3 nmol/g) than in vehicle-treated rats (17±1 counts/min per milligram and 24±3 nmol/g). Concurrent administration of an AT
1
receptor antagonist, valsartan (30 mg/kg per day, in drinking water), to CysA-treated rats (n=7) significantly decreased SBP (113±4 mm Hg) and prevented increases in vascular superoxide (16±2 counts/min per milligram) and kidney TBARS contents (21±3 nmol/g). Similarly, treatment with a superoxide dismutase mimetic, 4-hydroxy-2,2,6,6,-tetramethylpiperidine-N-oxyl (Tempol; 3 mmol/L in drinking water, n=7), prevented CysA-induced increases in SBP (115±3 mm Hg), vascular superoxide (16±1 counts/min per milligram), and kidney TBARS contents (19±2 nmol/g). These data suggest that ROS generation induced by augmented Ang II levels contributes to the development of CysA-induced hypertension.
Low-Dose Angiotensin II Enhances Pressor Responses Without Causing Sustained Hypertension
Authors: Pelaez Laura I. , Manriquez Melissa C. , Nath Karl A. , Romero Juan C. , Juncos Luis A.
Published: July 2003

Subpressor doses of angiotensin II (SP-Ang II) cause a slow increase in blood pressure in rats as assessed by tail cuff plethysmography (TCP), reflecting either sustained hypertension or an exaggerated pressor response to diverse stimuli. We examined whether subpressor doses of Ang II enhance blood pressure responses to simple stress (handling of trained rats for TCP). We implanted telemetry in Sprague-Dawley rats. After 10 days of recovery and TCP training, we implanted osmotic minipumps with either SP-Ang II (50 ng/kg per minute) or vehicle, and then measured systolic blood pressure continuously in unrestrained rats for 13 days. We also recorded telemetry readings while obtaining TCP measurements every 2 days. SP-Ang II increased blood pressure from 134±19 to 159±22 mm Hg by TCP, which matched the simultaneous telemetry readings of 131±20 to 154±25 mm Hg. In contrast, SP-Ang II did not change the blood pressure in the unrestrained rats (measured with continuous telemetry: 124±2 versus 127±1 mm Hg). The blood pressure in the control rats did not change in the unrestrained state (125±3 versus 128±5 mm Hg on days 0 and 12, respectively), and only slightly increased during TCP (11±5 and 6±4 mm Hg by TCP and simultaneous telemetry, respectively;
P
=NS). In summary, SP-Ang II, although unable to provoke sustained hypertension, nonetheless magnifies the pressor response to otherwise trivial stimuli. We speculate that even modestly elevated Ang II levels may contribute to hypertensive complications because such levels promote the punctuation of an apparent normotensive state by episodic hypertension occasioned by seemingly innocuous stimuli.
Betacellulin and Amphiregulin Induce Upregulation of Cyclin D1 and DNA Synthesis Activity Through Differential Signaling Pathways in Vascular Smooth Muscle Cells
Authors: Shin Hyoung Seek , Lee Hyo Jeong , Nishida Makoto , Lee Mi-Sook , Tamura Ritsu , Yamashita Shizuya , Matsuzawa Yuji , Lee In-Kyu , Koh Gou Young
Published: July 2003

Activation of EGF receptors is closely involved in vascular proliferative diseases. The signaling mechanisms of EGF ligands, including betacellulin (BTC) and amphiregulin (AR), are poorly understood. We examined how BTC and AR induced DNA synthesis activity in primary cultures of human thoracic aortic smooth muscle cells (HTASMCs). BTC induced phosphorylation of all four EGF receptors present on HTASMCs: ErbB1, ErbB2, ErbB3, and ErbB4. BTC rapidly induced the phosphorylation of Akt, GSK3α/β, and two FoxO factors, FKHR and AFX, in a dose- and time-dependent manner. BTC increased nuclear β-catenin accumulation. BTC increased cyclin D1 mRNA, cyclin D1 protein, and DNA synthesis activity. Pretreatment with the phosphatidylinositol 3′-kinase (PI 3′-kinase) inhibitor wortmannin suppressed BTC-induced cyclin D1 mRNA and protein and DNA synthesis activity. In contrast, AR, a specific ErbB1 ligand, induced sustained ERK1/2 and Elk1 phosphorylation, increased cyclin D1 mRNA and protein, and increased DNA synthesis activity. AR did not produce any changes in Akt phosphorylation. Pretreatment with PD98059 suppressed AR-induced cyclin D1 mRNA and protein. Thus, the PI 3′-kinase/Akt/GSK/FoxO/β-catenin pathway could be the major signaling cascade for BTC-induced upregulation of cyclin D1 protein, whereas a sustained ERK/Elk1 activation could be the major signaling cascade for AR-induced upregulation of cyclin D1 protein in HTASMCs. Moreover, immunohistochemical staining revealed that that BTC, ErbB1, and ErbB4 are upregulated in the plaques of human atherosclerotic coronary arteries. Taken together, BTC and AR could be potent growth factors in proliferative vascular diseases.
The Antianginal Agent Trimetazidine Does Not Exert Its Functional Benefit via Inhibition of Mitochondrial Long-Chain 3-Ketoacyl Coenzyme A Thiolase
Authors: MacInnes Alan , Fairman David A. , Binding Peter , Rhodes Jo ann , Wyatt Michael J. , Phelan Anne , Haddock Peter S. , Karran Eric H.
Published: July 2003

Trimetazidine acts as an effective antianginal clinical agent by modulating cardiac energy metabolism. Recent published data support the hypothesis that trimetazidine selectively inhibits long-chain 3-ketoacyl CoA thiolase (LC 3-KAT), thereby reducing fatty acid oxidation resulting in clinical benefit. The aim of this study was to assess whether trimetazidine and ranolazine, which may also act as a metabolic modulator, are specific inhibitors of LC 3-KAT. We have demonstrated that trimetazidine and ranolazine do not inhibit crude and purified rat heart or recombinant human LC 3-KAT by methods that both assess the ability of LC 3-KAT to turnover specific substrate, and LC 3-KAT activity as a functional component of intact cellular β-oxidation. Furthermore, we have demonstrated that trimetazidine does not inhibit any component of β-oxidation in an isolated human cardiomyocyte cell line. Ranolazine, however, did demonstrate a partial inhibition of β-oxidation in a dose-dependent manner (12% at 100 μmol/L and 30% at 300 μmol/L). Both trimetazidine (10 μmol/L) and ranolazine (20 μmol/L) improved the recovery of cardiac function after a period of no flow ischemia in the isolated working rat heart perfused with a buffer containing a relatively high concentration (1.2 mmol/L) of free fatty acid. In summary, both trimetazidine and ranolazine were able to improve ischemic cardiac function but inhibition of LC 3-KAT is not part of their mechanism of action. The full text of this article is available online at http://www.circresaha.org.
Beneficial Effects of Trimetazidine in Ex Vivo Working Ischemic Hearts Are Due to a Stimulation of Glucose Oxidation Secondary to Inhibition of Long-Chain 3-Ketoacyl Coenzyme A Thiolase
Authors: Lopaschuk Gary D. , Barr Rick , Thomas Panakkezhum D. , Dyck Jason R.B.
Published: July 2003

High rates of fatty acid oxidation in the heart and subsequent inhibition of glucose oxidation contributes to the severity of myocardial ischemia. These adverse effects of fatty acids can be overcome by stimulating glucose oxidation, either directly or secondary to an inhibition of fatty acid oxidation. We recently demonstrated that trimetazidine stimulates glucose oxidation in the heart secondary to inhibition of fatty acid oxidation. This inhibition of fatty acid oxidation was attributed to an inhibition of mitochondrial long-chain 3-ketoacyl CoA thiolase (LC 3-KAT), an enzyme of fatty acid β-oxidation. However, the accompanying Research Commentary of MacInnes et al suggests that trimetazidine does not inhibit cardiac LC 3-KAT. This discrepancy with our data can be attributed to the reversible competitive nature of trimetazidine inhibition of LC 3-KAT. In the presence of 2.5 μmol/L 3-keto-hexadecanoyl CoA (KHCoA), trimetazidine resulted in a 50% inhibition of LC-3-KAT activity. However, the inhibition of LC 3-KAT could be completely reversed by increasing substrate (3-keto-hexadecanoyl CoA, KHCoA) concentrations to 15 μmol/L even at high concentrations of trimetazidine (100 μmol/L). The study of MacInnes et al was performed using concentrations of 3K-HCoA in excess of 16 μmol/L, a concentration that would completely overcome 100 μmol/L trimetazidine inhibition of LC 3-KAT. Therefore, the lack of inhibition of LC 3-KAT by trimetazidine in the MacInnes et al study can easily be explained by the high concentration of KHCoA substrate used in their experiments. In isolated working hearts perfused with high levels of fatty acids, we found that trimetazidine (100 μmol/L) significantly improves functional recovery of hearts subjected to a 30-minute period of global no-flow ischemia. This occurred in the absence of changes in oxygen consumption resulting in an improved increase in cardiac efficiency. Combined with our previous studies, we conclude that trimetazidine inhibition of LC 3-KAT decreases fatty acid oxidation and stimulates glucose oxidation, resulting in an improvement in cardiac function and efficiency after ischemia. The full text of this article is available online at http://www.circresaha.org.
Ca
v
3.1 (α
1G
) T-Type Ca
2+
Channels Mediate Vaso-Occlusion of Sickled Erythrocytes in Lung Microcirculation
Authors: Wu Songwei , Haynes Johnson , Taylor James T. , Obiako Boniface O. , Stubbs James R. , Li Ming , Stevens Troy
Published: July 2003

In the present study, we demonstrate that lung microvascular endothelial cells express a Ca
v
3.1 (α
1G
) T-type voltage-gated Ca
2+
channel, whereas lung macrovascular endothelial cells do not express voltage-gated Ca
2+
channels. Voltage-dependent activation indicates that the Ca
v
3.1 T-type Ca
2+
current is shifted to a positive potential, at which maximum current activation is −10 mV; voltage-dependent conductance and inactivation properties suggest a “window current” in the range of −60 to −30 mV. Thrombin-induced transitions in membrane potential activate the Ca
v
3.1 channel, resulting in a physiologically relevant rise in cytosolic Ca
2+
. Furthermore, activation of the Ca
v
3.1 channel induces a procoagulant endothelial phenotype; eg, channel inhibition attenuates increased retention of sickled erythrocytes in the inflamed pulmonary circulation. We conclude that activation of the Ca
v
3.1 channels selectively induces phenotypic changes in microvascular endothelial cells that mediate vaso-occlusion by sickled erythrocytes in the inflamed lung microcirculation.
Development and Progression of Leukoaraiosis in Patients With Brain Ischemia and Carotid Artery Disease
Authors: Streifler Jonathan Y. , Eliasziw Michael , Benavente Oscar R. , Alamowitch Sonia , Fox Allan J. , Hachinski Vladimir , Barnett Henry J.M.
Published: July 2003

Background and Purpose—

Leukoaraiosis (LA) or the presence of white matter changes, a frequent finding on brain CT scans of elderly individuals, is a risk factor for stroke and vascular death. The aim of the study was to seek development and progression of LA and associated risk factors in patients with symptomatic carotid artery disease.

Methods—

Presence and extent of LA were determined on entry and follow-up CT scans from 685 patients in the North American Symptomatic Carotid Endarterectomy Trial.

Results—

Among 596 patients without LA at entry, 107 (18.0%) developed restricted LA and 18 (3.0%) developed widespread LA during a mean follow-up of 6.1 years (range, 3.0 to 9.6 years). Older age was associated significantly with LA development (
P
<0.001). History of hypertension, diabetes mellitus, ischemic heart disease, and intermittent claudication had weak associations with LA development. During follow-up, 36.0% of patients who developed LA had 1 or more strokes, particularly of the lacunar type, in comparison to 23.5% of patients who did not develop LA (
P
=0.01). In patients who developed LA, the percentage with small deep infarcts (diameter ≤1.5 cm) increased from 34.4% on entry to 45.6% on follow-up CT scans compared with no increase (20.4% and 20.4%, respectively) in patients who did not develop LA. Among 89 patients who had restricted LA at entry, 28 (31.5%) progressed to widespread LA. Progression was associated with occurrence of strokes.

Conclusions—

LA is common in elderly patients with symptomatic cerebrovascular disease. Its development and progression are associated with higher occurrence of strokes, mainly of the lacunar type.
Association between acute and chronic graft-versus-host disease and bronchiolitis obliterans organizing pneumonia in recipients of hematopoietic stem cell transplants
Authors: Freudenberger Todd D. , Madtes David K. , Curtis J. Randall , Cummings Peter , Storer Barry E. , Hackman Robert C.
Published: July 2003

Bronchiolitis obliterans organizing pneumonia (BOOP) has been reported following hematopoietic stem cell (HSC) transplantation, but the clinical features and risk factors for this disorder have not been well characterized. This case-control study of 49 patients with histologic BOOP and 161 control subjects matched by age and year of transplantation describes the clinical features and analyzes the risk factors for BOOP following HSC transplantation. Data on clinical features and outcome were collected by chart review. Odds ratios, estimating the relative risk of BOOP in allogeneic HSC recipients, were calculated by conditional logistic regression with adjustment for potential confounding factors. Clinical features of BOOP in this population were similar to idiopathic BOOP and BOOP occurring in other disease settings. There was an association between acute and chronic graft-versus-host disease (GVHD) and the subsequent development of BOOP (odds ratios, 3.8 [95% CI, 1.2 to 12.3] and 3.1 [95% CI, 1.1 to 9.2], respectively). Patients with BOOP were more likely to have acute GVHD involving the skin (odds ratio, 4.6; P = .005) and chronic GVHD involving the gut (odds ratio, 6.6; P = .018) and oral cavity (odds ratio, 5.9; P = .026). This study shows that histologic BOOP following HSC transplantation has clinical features that resemble idiopathic BOOP and is strongly associated with prior acute and chronic GVHD. These results have important implications for the care of patients who develop respiratory symptoms after HSC transplantation and may help elucidate the pathogenesis of idiopathic BOOP. (Blood. 2003;102:3822-3828)
Late diversification in the clonal composition of human cytomegalovirus-specific CD8+ T cells following allogeneic hemopoietic stem cell transplantation
Authors: Gandhi Maher K. , Wills Mark R. , Okecha Georgina , Day Elizabeth K. , Hicks Ray , Marcus Robert E. , Sissons J. G. Patrick , Carmichael Andrew J.
Published: July 2003

To investigate the mechanisms of human T-cell reconstitution following allogeneic hemopoietic stem cell transplantation (alloSCT), we analyzed the clonal composition of human cytomegalovirus (HCMV)-specific or Epstein-Barr virus (EBV)-specific CD8+ T cells in 10 alloSC transplant recipients and their donors. All virus-specific CD8+ T-cell clones isolated from recipients after alloSCT contained DNA of donor origin. In all 6 D+/R+ sibling alloSCTs from seropositive donors into seropositive recipients, donor virus-specific clones transferred in the allograft underwent early expansion and were maintained long term in the recipient. In contrast, in 2 of 3 HCMV D+/R- alloSC transplant recipients in whom there was no detectable HCMV infection, donor HCMV-specific clones were undetectable, whereas donor EBV-specific clones were maintained in the same EBV-seropositive recipients, suggesting that transferred clones require antigen for their maintenance. Following D-/R+ transplantation from 3 seronegative donors into seropositive recipients, a delayed primary virus-specific CD8+ T-cell response was observed, in which the T cells contained donor DNA, suggesting that new antigen-specific T cells arose in the recipient from donor-derived progenitors. In 2 of 4 HCMV D+/R+ sibling allograft recipients the clonal composition underwent diversification as compared with their donors, with delayed persistent expansion of HCMV-specific clones that were undetectable in the donor or in the recipient during the early months after transplantation; this diversification may represent expansion of new clones generated from donor-derived progenitors. We conclude that, following alloSCT, late diversification of the HCMV-specific CD8+ T-cell clonal repertoire can occur in response to persistent viral antigen.
Attenuated signaling by a phosphotyrosine-null Epo receptor form in primary erythroid progenitor cells
Authors: Li Ke , Menon Madhu P. , Karur Vinit G. , Hegde Shailaja , Wojchowski Don M.
Published: July 2003

Signals provided by the erythropoieitin receptor (EpoR) are required for erythroid development beyond the erythroid colony-forming unit (CFU-e) stage and are propagated via the EpoR-tethered Janus kinase, JAK2. JAK2 functions, in part, to phosphorylate 8 conserved EpoR phosphotyrosine (PY) sites for the binding of a diverse set of signaling factors. However, recent studies in transgenic and knock-in mice have demonstrated substantial bioactivity for PY-null EpoR forms. Presently, the activities of a PY-null EpoR-HM form in primary progenitor cells from knock-in mice were further assessed using optimized Epo dose-dependent proliferation, survival, and differentiation assays. As compared with the wild-type (wt)–EpoR, EpoR-HM activity was compromised several-fold in each context when Epo was limited to physiologic concentrations. Possible compensatory increases in serum growth factor levels also were investigated, and as assayed using embryonic stem (ES) cell–derived erythroid G1E2 cells, activities in serum from EpoR-HM mice were substantially elevated. In addition, when challenged with phenylhydrazine-induced anemia, EpoR-HM mice failed to respond with efficient splenic stress erythropoiesis. Thus, the function of this JAK2-coupled but minimal PY-null EpoR-HM form appears to be attenuated in several contexts and to be assisted in vivo by compensatory mechanisms. Roles normally played by EpoR PY sites and distal domains therefore should receive continued attention.
Antiphospholipid/antiprotein antibodies, hemostasis-related autoantibodies, and plasma homocysteine as risk factors for a first early pregnancy loss: a matched case-control study
Authors: Gris Jean-Christophe , Perneger Thomas V. , Quéré Isabelle , Mercier Eric , Fabbro-Peray Pascale , Lavigne-Lissalde Géraldine , Hoffet Médéric , Déchaud Hervé , Boyer Jean-Christophe , Ripart-Neveu Sylvie , Tailland Marie-Laure , Daurès Jean-Pierre , Marès Pierre , Dauzat Michel
Published: July 2003

Maternal hypercoagulability is a possible cause of miscarriage during the eighth and ninth weeks of pregnancy, when the placenta replaces the yolk sac. We thus examined associations between putative markers of an acquired hypercoagulable state and the risk of first miscarriage. We conducted a case-control study comparing 743 women who miscarried in weeks 8 and 9 with 743 women who underwent a first provoked abortion, matched for age, number of pregnancies, and time elapsed since abortion. Levels of plasma homocysteine and of various antiphospholipid/antiprotein and hemostasis-related autoantibodies were categorized in 4 strata (percentiles 1-80, 81-95, 96-99, 100 among control patients) and analyzed in conditional logistic regression models. Pregnancy loss was independently associated with positive lupus anticoagulant (matched odds ratio [OR], 2.6; 95% confidence interval [CI], 1.1-6.0), high levels of immunoglobulin M (IgM) antibodies against cardiolipin (OR for percentile 100 versus 0-80, 3.5; CI, 1.2-10.1) and against phosphatidylethanolamine (OR, 4.7; CI, 1.9-12.1), high levels of IgG antibodies against annexin V (OR, 3.2; CI, 1.1-9.1) and against tissue-type plasminogen activator (OR, 19.5; CI, 7.9-48.0), and high homocystinemia (OR, 4.1; CI, 1.3-12.5). A first early pregnancy loss is associated with increased levels of several autoantibodies and of homocysteine. (Blood. 2003;102:3504-3513)
Human dendritic cell subsets in NOD/SCID mice engrafted with CD34+ hematopoietic progenitors
Authors: Palucka A. Karolina , Gatlin Joel , Blanck Jean Philippe , Melkus Michael W. , Clayton Sandra , Ueno Hideki , Kraus Elizabeth T. , Cravens Petra , Bennett Lynda , Padgett-Thomas Angela , Marches Florentina , Islas-Ohlmayer Miguel , Garcia J. Victor , Banchereau Jacques
Published: July 2003

Distinct human dendritic cell (DC) subsets differentially control immunity. Thus, insights into their in vivo functions are important to understand the launching and modulation of immune responses. We show that nonobese diabetic/LtSz-scid/scid (NOD/SCID) mice engrafted with human CD34+ hematopoietic progenitors develop human myeloid and plasmacytoid DCs. The skin displays immature DCs expressing Langerin, while other tissues display interstitial DCs. Myeloid DCs from these mice induce proliferation of allogeneic CD4 T cells in vitro, and bone marrow human cells containing plasmacytoid DCs release interferon-α (IFN-α) upon influenza virus exposure. Injection of influenza virus into reconstituted mice triggers IFN-α release and maturation of mDCs. Thus, these mice may provide a model to study the pathophysiology of human DC subsets.
G-protein-coupled receptor S1P1 acts within endothelial cells to regulate vascular maturation
Authors: Allende Maria L. , Yamashita Tadashi , Proia Richard L.
Published: July 2003

Sphingosine-1-phosphate (S1P) stimulates signaling pathways via G-protein-coupled receptors and triggers diverse cellular processes, including growth, survival, and migration. In S1P1 receptor-deficient embryos, blood vessels were incompletely covered by vascular smooth muscle cells (VSMCs), indicating the S1P1 receptor regulates vascular maturation. Because S1P1 receptor expression is not restricted to a particular cell type, it was not known whether the S1P1 receptor controlled VSMC coverage of vessels in a cell-autonomous fashion by functioning directly in VSMCs or indirectly through its activity in endothelial cells (ECs). By using the Cre/loxP system, we disrupted the S1P1 gene solely in ECs. The phenotype of the conditional mutant embryos mimicked the one obtained in the embryos globally deficient in S1P1. Thus, vessel coverage by VSMCs is directed by the activity of the S1P1 receptor in ECs. (Blood. 2003;102:3665-3667)
Cooperative signaling between cytokine receptors and the glucocorticoid receptor in the expansion of erythroid progenitors: molecular analysis by expression profiling
Authors: Kolbus Andrea , Blázquez-Domingo Montserrat , Carotta Sebastian , Bakker Walbert , Luedemann Susanna , von Lindern Marieke , Steinlein Peter , Beug Hartmut
Published: July 2003

Erythroid progenitors undergo renewal (proliferation without apparent differentiation) in response to erythropoietin (Epo), stem cell factor (SCF), and glucocorticoids (dexamethasone) (Dex). SCF and Dex cooperate with Epo to promote proliferation and inhibit differentiation of erythroid progenitors, while Epo alone is required to protect erythroid cells from apoptosis during terminal red cell maturation. To examine the mechanism of the synergistic interactions of Epo, SCF, and Dex, we analyzed gene expression patterns using DNA chip–based large-scale comparative gene profiling using microarrays enriched in hematopoietic transcripts or containing randomly selected genes. Differentially regulated genes were validated by real-time reverse transcription–polymerase chain reaction (RT-PCR). The results reveal cooperative regulation of gene expression by glucocorticoids and Epo/SCF on a number of genes, such as CIS, BTG1, VDUP1, CXCR4, GILZ, and RIKEN29300106B05. While Epo and SCF never showed opposite effects on gene expression, Dex either enhanced or attenuated the effect of Epo and/or SCF. Several glucocorticoid receptor (GR)–target genes were regulated by Dex only in the presence of Epo and/or SCF, suggesting that the GR functions in the context of a larger transactivation complex to regulate these genes. The data also suggest that modulation of cytokine-induced signals by the GR is an important mechanism in erythroid progenitor renewal.
Improved hemostasis with superactive analogs of factor VIIa in a mouse model of hemophilia A
Authors: Tranholm Mikael , Kristensen Kim , Kristensen Annemarie T. , Pyke Charles , Røjkjær Rasmus , Persson Egon
Published: July 2003

It is currently debated whether the mechanism of action of therapeutic doses of recombinant factor VIIa (rFVIIa, Novo-Seven) relies on the tissue factor (TF)-independent activity of the enzyme. The present study was conducted to investigate the in vivo hemostatic effects of rFVIIa and 3 analogs thereof with superior intrinsic activity (FVIIaIIa, K337A-FVIIaIia, and M298Q-FVIIa) in mice with antibody-induced hemophilia A. A highly significant dose response was observed for the bleeding time and blood loss for each of the rFVIIa variants. The bleeding time and blood loss were normalized after administration of 10 mg/kg rFVIIa, 3 mg/kg K337A-FVIIaIia, and 3 mg/kg M298Q-FVIIa, indicating a potency of these FVIIa analogs 3-4 times above that of rFVIIa in FVIII-depleted mice. The different in vivo potencies of the various forms of FVIIa could not be explained by the pharmacokinetics. Histopathological evaluation of kidneys revealed no signs of treatment-related pathological changes even after treatment with the superactive variants. The fact that FVIIa analogs with enhanced intrinsic activity are more efficacious in the murine hemophilia A model strongly suggests that the TF-independent procoagulant activity of FVIIa contributes to its clinical hemostatic effect. (Blood. 2003; 102:3615-3620)
Generation of an erythrocyte vesicle transport system by Plasmodium falciparum malaria parasites
Authors: Taraschi Theodore F. , O'Donnell Megan , Martinez Sandra , Schneider Timothy , Trelka Darin , Fowler Velia M. , Tilley Leann , Moriyama Yoshinori
Published: July 2003

The asexual maturation of Plasmodium falciparum is accompanied by the transport of parasite-encoded proteins to the erythrocyte plasma membrane. Activation of G proteins by treatment with aluminum fluoride produced an accumulation within the erythrocyte cytosol of vesicles coated with Plasmodium homologues of COPII and N-ethylmaleimide-sensitive factor, proteins involved in intracellular transport between the Golgi apparatus and the endoplasmic reticulum. These vesicles contain malarial proteins that appear on the erythrocyte plasma membrane, as well as actin and myosin. It is proposed that the parasite adapted a process well established for intracellular transport to mediate the extracellular movement of its proteins through the erythrocyte cytosol to the surface membrane.
Survival advantage associated with heterozygous factor V Leiden mutation in patients with severe sepsis and in mouse endotoxemia
Authors: Kerlin Bryce A. , Yan S. Betty , Isermann Berend H. , Brandt John T. , Sood Rashmi , Basson Bruce R. , Joyce David E. , Weiler Hartmut , Dhainaut Jean-Francois
Published: July 2003

Sepsis is associated with systemic inflammation, coagulopathy, and disrupted protein C (PC) pathway function. The effect of prothrombotic polymorphism, factor V Leiden (Arg506Gln; FV Leiden), was examined in a large clinical trial (PROWESS) of severe sepsis and a mouse endotoxemia model. In PROWESS, 4.1% (n = 65) of patients were heterozygous FV Leiden (VL+/–) carriers. The 28-day mortality was lower in VL+/– (13.9%) than in non-FV Leiden (VL–/–; 27.9%) patients (P = .013). The mortality benefit of recombinant human activated PC (rhAPC) treatment was similar in VL+/– (placebo, 15.6%; rhAPC,12.1%) and VL–/– patients (placebo, 31.0%; rhAPC, 24.7%; interaction P = .981). VL+/– status did not appear to influence baseline biomarkers of coagulopathy and inflammation or disease severity, with the exception that vasopressor usage was less in VL+/– patients (46.2% versus 63.0%; P = .009). In a median lethal dose (40 mg/kg) endotoxin mouse model, VL+/– mice had lower mortality than wild-type mice (19% versus 57%; P = .008), whereas the mortality of homozygous (VL+/+) mice was almost identical to that of wild-type mice (65% versus 57%; P = .76). The findings suggest that FV Leiden constitutes a rare example of a balanced gene polymorphism that maintains the FV Leiden mutation in the general gene pool due to a survival advantage of VL+/– in severe sepsis.