bluuebunny/crossref_metadata_2025 huggingface dataset:
ANG II in the paraventricular nucleus potentiates the cardiac sympathetic afferent reflex in rats with heart failure
Authors: Zhu Guo-Qing , Gao Lie , Patel Kuashik P. , Zucker Irving H. , Wang Wei
Published: October 2004

Chronic heart failure (CHF) is characterized by sympathoexcitation, and the cardiac sympathetic afferent reflex (CSAR) is a sympathoexcitatory reflex. Our previous studies have shown that the CSAR was enhanced in CHF. In addition, central angiotensin II (ANG II) is an important modulator of this reflex. This study was performed to determine whether the CSAR evoked by stimulation of cardiac sympathetic afferent nerves (CSAN) in rats with coronary ligation-induced CHF is enhanced by ANG II in the paraventricular nucleus (PVN). Under α-chloralose and urethane anesthesia, renal sympathetic nerve activity (RSNA) was recorded. The RSNA responses to electrical stimulation (5, 10, 20, and 30 Hz) of the CSAN were evaluated. Bilateral microinjection of the AT1-receptor antagonist losartan (50 nmol) into the PVN had no significant effects in the sham group, but it abolished the enhanced RSNA response to stimulation in the CHF group. Unilateral microinjection of three doses of ANG II (0.03, 0.3, and 3 nmol) into the PVN resulted in dose-related increases in the RSNA responses to stimulation. Although ANG II also potentiated the RSNA response to electrical stimulation in sham rats, the RSNA responses to stimulation after ANG II into the PVN in rats with CHF were much greater than in sham rats. The effects of ANG II were prevented by pretreatment with losartan into the PVN in CHF rats. These results suggest that the central gain of the CSAR is enhanced in rats with coronary ligation-induced CHF and that ANG II in the PVN augments the CSAR evoked by CSAN, which is mediated by the central angiotensin AT1 receptors in rats with CHF.
Twitch potentiation is greater after a fatiguing submaximal isometric contraction performed at short vs. long quadriceps muscle length
Authors: Place Nicolas , Maffiuletti Nicola A. , Ballay Yves , Lepers Romuald
Published: October 2004

Endurance time of a submaximal sustained contraction is longer when the muscle is fatigued in a shortened position. The aim of the present study was to compare central and peripheral mechanisms of fatigue after an isometric contraction of the knee extensor muscles performed at 20% maximal voluntary contraction (MVC) at two knee angles (35°, short length vs. 75°, long length; 0° = full extension) until exhaustion. Eleven men (24 ± 4 yr) attended two experimental randomized sessions. Endurance time was greater at 35° compared with 75° (974 ± 457 vs. 398 ± 144 s; P < 0.001) despite a similar reduction in knee extensor MVC (−28.4 ± 16.0%, P < 0.001 vs. −27.6 ± 18.8%, P < 0.001, respectively). Voluntary activation level was similarly depressed after the fatiguing contraction performed at the two muscle lengths (−19 ± 16.7% at 35°, P < 0.01 vs. −13.7 ± 14.5% at 75°, P < 0.01). After the fatiguing contraction, peak twitch potentiation was observed only at the short length (+31.8 ± 17.6% at 35°, P < 0.01 vs. +6.4 ± 21.3% at 75°, P > 0.05), whereas M-wave properties were similarly altered for the two angles. These results suggest that 1) central fatigue at task failure for a sustained isometric contraction was not dependent on the muscle length, and 2) the longer endurance time of a sustained isometric contraction performed at a shortened length is related to potentiation. It is suggested that the greater endurance time of a sustained isometric contraction observed at 35° is related to the occurrence of potentiation at this short length, because central fatigue is similar at task failure for both tasks.
Hematological and acid-base changes in men during prolonged exercise with and without sodium-lactate infusion
Authors: Miller Benjamin F. , Lindinger Michael I. , Fattor Jill A. , Jacobs Kevin A. , LeBlanc Paul J. , Duong MyLinh , Heigenhauser George J. F. , Brooks George A.
Published: October 2004

An emerging technique used for the study of metabolic regulation is the elevation of lactate concentration with a sodium-lactate infusion, the lactate clamp (LC). However, hematological and acid-base properties affected by the infusion of hypertonic solutions containing the osmotically active strong ions sodium (Na+) and lactate (Lac−) are a concern for clinical and research applications of LC. In the present study, we characterized the hematological and plasma acid-base changes during rest and prolonged, light- to moderate-intensity (55% V̇o2 peak) exercise with and without LC. During the control (Con) trial, subjects were administered an isotonic, isovolumetric saline infusion. During LC, plasma lactate concentration ([Lac−]) was elevated to 4 meq/l during rest and to 4–7 meq/l during exercise. During LC at rest, there were rapid and transient changes in plasma, erythrocyte, and blood volumes. LC resulted in decreased plasma [H+] (from 39.6 to 29.6 neq/l) at the end of exercise while plasma [HCO3−] increased from 26 to 32.9 meq/l. Increased plasma strong ion difference [SID], due to increased [Na+], was the primary contributor to decreased [H+] and increased [HCO3−]. A decrease in plasma total weak acid concentration also contributed to these changes, whereas Pco2 contributed little. The infusion of hypertonic LC caused only minor volume, acid-base, and CO2 storage responses. We conclude that an LC infusion is appropriate for studies of metabolic regulation.
C57BL/6J and B6.V-LEPOB mice differ in the cholinergic modulation of sleep and breathing
Authors: Douglas Christopher L. , Bowman Grant N. , Baghdoyan Helen A. , Lydic Ralph
Published: October 2004

Respiratory and arousal state control are heritable traits in mice. B6.V-Lepob (ob) mice are leptin deficient and differ from C57BL/6J (B6) mice by a variation in the gene coding for leptin. The ob mouse has morbid obesity and disordered breathing that is homologous to breathing of obese humans. This study tested the hypothesis that microinjecting neostigmine into the pontine reticular nucleus, oral part (PnO), of B6 and ob mice alters sleep and breathing. In B6 and ob mice, neostigmine caused a concentration-dependent increase ( P < 0.0001) in percentage of time spent in a rapid eye movement (REM) sleeplike state (REM-Neo). Relative to saline (control), higher concentrations of neostigmine increased REM-Neo duration and the number of REM-Neo episodes in B6 and ob mice and decreased percent wake, percent non-REM, and latency to onset of REM-Neo ( P < 0.001). In B6 and ob mice, REM sleep enhancement by neostigmine was blocked by atropine. Differences in control amounts of sleep and wakefulness between B6 and the congenic ob mice also were identified. After PnO injection of saline, ob mice spent significantly ( P < 0.05) more time awake and less time in non-REM sleep. B6 mice displayed more ( P < 0.01) baseline locomotor activity than ob mice, and PnO neostigmine decreased locomotion ( P < 0.0001) in B6 and ob mice. Whole body plethysmography showed that PnO neostigmine depressed breathing ( P < 0.001) in B6 and ob mice and caused greater respiratory depression in B6 than ob mice ( P < 0.05). Western blot analysis identified greater ( P < 0.05) expression of M2 muscarinic receptor protein in ob than B6 mice for cortex, midbrain, cerebellum, and pons, but not medulla. Considered together, these data provide the first evidence that pontine cholinergic control of sleep and breathing varies between mice known to differ by a spontaneous mutation in the gene coding for leptin.
Absence of left ventricular and arterial adaptations to exercise in octogenarians
Authors: Spina Robert J. , Meyer Timothy E. , Peterson Linda R. , Villareal Dennis T. , Rinder Morton R. , Ehsani Ali A.
Published: October 2004

Recent evidence suggests that octogenarians exhibit attenuated adaptations to training with a small increase in peak O2 consumption (V̇o2) that is mediated by a modest improvement in cardiac output without an increase in arteriovenous O2 content difference. This study was designed to determine whether diminished increases in peak V̇o2 and cardiac output in the octogenarians are associated with absence of left ventricular and arterial adaptations to exercise training. We studied 22 octogenarians (81.9 ± 3.7 yr, mean ± SD) randomly assigned a group that exercised at an intensity of 82.5 ± 5% of peak heart rate for 9 mo and 14 (age 83.1 ± 4.1) assigned to a control group. Peak V̇o2 increased 12% in the exercise group but decreased slightly (−7%) in the controls. The exercise group demonstrated significant but small decreases in the heart rate (6%, P = 0.002) and the rate-pressure product (9%, P = 0.004) during submaximal exercise at an absolute work rate. Training induced no significant changes in the left ventricular size, geometry (wall thickness-to-radius ratio), mass, and function assessed with two-dimensional echocardiography or in arterial stiffness evaluated with applanation tonometry. Data suggest that the absence of cardiac and arterial adaptations may in part account for the limited gain in aerobic capacity in response to training in the octogenarians.
Decorin Promotes Aortic Smooth Muscle Cell Calcification and Colocalizes to Calcified Regions in Human Atherosclerotic Lesions
Authors: Fischer Jens W. , Steitz Susie A. , Johnson Pamela Y. , Burke Allen , Kolodgie Frank , Virmani Renu , Giachelli Cecilia , Wight Thomas N.
Published: October 2004

Objective—

Ectopic calcification localized to the intima of atherosclerotic plaque is a risk marker for cardiovascular events and increases the risk of aortic dissection during angioplasty. A variety of extracellular matrix molecules such as collagen type 1, bone sialoprotein, and osteopontin are known to regulate the biomineralization of bone and ectopic vascular calcification. In the present study, it was investigated whether decorin, a small leucine-rich proteoglycan expressed in bone and atherosclerotic plaque, is involved in arterial calcification.

Methods and Results—

Calcification was induced in cultured bovine aortic smooth muscle cell (BASMC) by the addition of β-glycerophosphate or inorganic phosphate. Northern and Western analysis revealed that decorin expression was strongly upregulated in mineralizing BASMC. Furthermore, overexpression of decorin using a retroviral expression vector resulted in a 3- to 4-fold elevation of calcium deposited on the BASMC monolayer. Increased calcification in response to decorin could also be mimicked by adding exogenous decorin to the cultures. In addition, human coronary atherosclerotic lesions taken from sudden-death patients showed marked colocalization of calcium deposits with decorin.

Conclusions—

Decorin induces calcification of arterial smooth muscle cell cultures and colocalizes to mineral deposition in human atherosclerotic plaque, suggesting that decorin functions as promoter of intimal calcification.
Quantitative and Qualitative Differences in Proatherogenic NKT Cells in Apolipoprotein E–Deficient Mice
Authors: Major Amy S. , Wilson Michael T. , McCaleb Jennifer L. , Ru Su Yan , Stanic Aleksandar K. , Joyce Sebastian , Van Kaer Luc , Fazio Sergio , Linton MacRae F.
Published: October 2004

Background—

Atherosclerosis is a disease marked by lipid accumulation and inflammation. Recently, atherosclerosis has gained recognition as an autoimmune-type syndrome characterized by increased activation of the innate and acquired immune systems. Natural killer T (NKT) cells have characteristics of both conventional T cells and NK cells and recognize glycolipid antigens presented in association with CD1d molecules on antigen-presenting cells. The capacity of NKT cells to respond to lipid antigens and modulate innate and acquired immunity suggests that they may play a role in atherogenesis.

Methods and Results—

We examined the role of NKT cells in atherogenesis and how the atherosclerotic environment affects the NKT cell population itself. The data show that CD1d-deficiency in male apolipoprotein E–deficient (apoE
0
) mice results in reduction in atherosclerosis, and treatment of apoE
0
mice with α-galactosylceramide, a potent and specific NKT cell activator, results in a 2-fold increase in atherosclerosis. Interestingly, we demonstrate that α-galactosylceramide–induced interferon-γ responses and numbers of NKT cells in apoE
0
mice show age-dependent qualitative and quantitative differences as compared with age-matched wild-type mice.

Conclusions—

Collectively, these findings reveal that hyperlipidemia and atherosclerosis have significant effects on NKT cell responses and that these cells are proatherogenic.
Intimal Thickness Is not Associated With Wall Shear Stress Patterns in the Human Right Coronary Artery
Authors: Joshi Anil K. , Leask Richard L. , Myers Jerry G. , Ojha Matadial , Butany Jagdish , Ethier C. Ross
Published: October 2004

Objective—

Low wall shear stress has been implicated in atherogenesis throughout the arterial tree, including the right coronary artery (RCA). The objective of this study was to determine the level of covariation of intimal thickness and wall shear stress in the human RCA.

Methods and Results—

Postmortem histological measurements of intimal thickness were compared with wall shear stresses calculated from computational flow modeling in 4 human right coronary arteries. A statistically significant correlation between intimal thickness and wall shear stress was found in only 1 of the 4 arteries studied.

Conclusion—

Wall shear stress does not appear to be related to intimal thickness in the 4 RCAs studied.
Overexpression of IL-18 Decreases Intimal Collagen Content and Promotes a Vulnerable Plaque Phenotype in Apolipoprotein-E–Deficient Mice
Authors: de Nooijer R. , von der Thüsen J.H. , Verkleij C.J.N. , Kuiper J. , Jukema J.W. , van der Wall E.E. , van Berkel Th.J.C. , Biessen E.A.L.
Published: October 2004

Objective—

Although IL-18 has been implicated in atherosclerotic lesion development, little is known about its role in advanced atherosclerotic plaques. This study aims to assess the effect of IL-18 overexpression on the stability of preexisting plaques.

Methods and Results—

Atherosclerotic lesions were elicited in carotid arteries of apolipoprotein E (apoE)-deficient mice (n=32) by placement of a perivascular collar. Overexpression of IL-18 was effected by intravenous injection of an adenoviral vector 5 weeks after surgery. Two weeks after transduction, lesions were analyzed histologically with regard to plaque morphology and composition or by real-time polymerase chain reaction. No difference in plaque size was detected between groups. In the Ad.IL-18–treated group, 62% of lesions displayed a vulnerable morphology or even intraplaque hemorrhage as compared with only 24% in the controls (
P
=0.037). In agreement, IL-18 overexpression reduced intimal collagen by 44% (
P
<0.003) and cap-to-core ratio by 41% (
P
<0.002). Although IL-18 did not affect the expression of collagen synthesis-related genes, it was found to enhance the collagenolytic activity of vascular smooth muscle cells in vitro, suggesting that the low collagen content is attributable to matrix degradation rather than to decreased synthesis.

Conclusion—

Systemic IL-18 overexpression markedly decreases intimal collagen content and cap thickness, leading to a vulnerable plaque morphology.
Helicobacter Pylori
Infection Causes Persistent Platelet Activation In Vivo Through Enhanced Lipid Peroxidation
Authors: Davì Giovanni , Neri Matteo , Falco Angela , Festi Davide , Taraborelli Tea , Ciabattoni Giovanni , Basili Stefania , Cuccurullo Franco , Patrono Carlo
Published: October 2004

Objective—

We aimed at investigating the relationship between
Helicobacter pylori
infection and in vivo lipid peroxidation and platelet activation, as reflected by urinary 8-iso-prostaglandin (PG)F
2α
and 11-dehydro-thromboxane (TX)B
2
, respectively, in otherwise healthy dyspeptic subjects.

Methods and Results—

We measured urinary 8-iso-PGF
2α
and 11-dehydro-TXB
2
excretion in 40 dyspeptic subjects with a positive
13
C-urea breath test and 38 dyspeptic individuals with a negative test. Moreover, we investigated the effects of
H pylori
eradication on prostanoid metabolite excretion in 23
H pylori
–positive subjects. We also measured prostanoid metabolite excretion before and after selective cyclooxygenase-2 inhibition with rofecoxib in 4
H pylori–
positive subjects. Urinary 8-iso-PGF
2α
and 11-dehydro-TXB
2
excretion was significantly higher in the
H pylori–
positive individuals than in controls. A significant direct correlation was found between the degree of positivity to the
13
C-urea breath test and urinary 8-iso-PGF
2α
excretion. The latter was linearly correlated with urinary 11-dehydro-TXB
2
. Successful eradication of
H pylori
infection led to a significant reduction in both 8-iso-PGF
2α
and 11-dehydro-TXB
2
. Furthermore, their levels were unaffected after treatment with rofecoxib.

Conclusions—

Our study provides evidence of enhanced in vivo lipid peroxidation and platelet activation in association with
H pylori
infection and suggests a novel mechanism by which an infectious agent could contribute to atherothrombosis.
Essential Role of Vascular Endothelial Growth Factor and Flt-1 Signals in Neointimal Formation After Periadventitial Injury
Authors: Zhao Qingwei , Egashira Kensuke , Hiasa Ken-ichi , Ishibashi Minako , Inoue Shujiro , Ohtani Kisho , Tan Chunyan , Shibuya Masabumi , Takeshita Akira , Sunagawa Kenji
Published: October 2004

Objective—

Vascular endothelial growth factor (VEGF) is upregulated after arterial injury. Its role in the pathogenesis of neointimal formation after periadventitial injury, however, has not been addressed.

Methods and Results—

Expression of VEGF and its receptors but not that of placental growth factor markedly increased with the development of neointimal formation in hypercholesterolemic mice after cuff-induced periarterial injury. Transfection with the murine soluble Flt-1 (sFlt-1) gene to block VEGF in vivo in mice inhibited early inflammation and later neointimal formation. The sFlt-1 gene transfer did not affect plasma lipid levels but attenuated increased expression of VEGF, Flt-1, Flk-1, monocyte chemoattractant protein-1, and other inflammation-promoting factors. Mice with Flt-1 kinase deficiency also displayed reduced neointimal formation.

Conclusions—

Inflammatory changes mediated by VEGF and Flt-1 signals play an important role in the pathogenesis of neointimal formation after cuff-induced periadventitial injury. VEGF might promote neointimal formation by acting as a proinflammatory cytokine.
Granzyme B Induces Smooth Muscle Cell Apoptosis in the Absence of Perforin
Authors: Choy Jonathan C. , Hung Vivian H.Y. , Hunter Arwen L. , Cheung Paul K. , Motyka Bruce , Goping Ing Swie , Sawchuk Tracy , Bleackley R. Chris , Podor Thomas J. , McManus Bruce M. , Granville David J.
Published: October 2004

Objective—T cell-induced cytotoxicity, of which granzyme B is a key mediator, is believed to contribute to the pathogenesis of inflammatory vascular diseases. In this report, we investigate the mechanism of granzyme B-induced smooth muscle cell (SMC) death.

Methods and Results—The addition of purified granzyme B alone to cultured SMCs caused a significant reduction in cell viability. Chromatin condensation, phosphatidylserine externalization, and membrane blebbing were observed, indicating that the mechanism of granzyme B-induced SMC death was through apoptosis. Activated splenocytes from perforin-knockout mice induced SMC death through a granzyme B-mediated pathway. Inhibition of the proteolytic activities of caspases and granzyme B prevented granzyme B-induced SMC death, whereas attenuation of granzyme B internalization with mannose-6-phosphate (M6P) did not. Further, granzyme B induced the cleavage of several SMC extracellular proteins, including fibronectin, and reduced focal adhesion kinase phosphorylation.

Conclusions—These results indicate that granzyme B can induce apoptosis of SMCs in the absence of perforin by cleaving extracellular proteins, such as fibronectin.
Maturation of Cardiovagal Autonomic Function From Childhood to Young Adult Age
Authors: Lenard Zsuzsanna , Studinger Peter , Mersich Beatrix , Kocsis Laszlo , Kollai Mark
Published: October 2004

Background—

Cardiovagal autonomic control declines with age in adult subjects, which is related in part to increasing stiffness of the barosensory vessel wall. It is not known, however, whether autonomic function changes with age in children.

Methods and Results—

We studied 137 healthy subjects divided into 4 age groups: group 1, 7 to 14 years; group 2, 11 to 14 years; group 3, 15 to 18 years; and group 4, 19 to 22 years. Brachial artery pressure was measured by sphygmomanometry and continuous radial artery pressure and carotid artery pulse pressure (ΔP) by applanation tonometry. The R-R interval was derived from the ECG. Autonomic function was assessed by spontaneous sequence and frequency-domain indices, which indicate the extent of coupling between fluctuations in heart rate and systolic pressure. Carotid artery diastolic diameter (DD) and pulsatile distension (ΔD) were measured by echo wall tracking; carotid compliance coefficient (CC) was defined as ΔD/ΔP and distensibility coefficient as 2ΔD/DD · ΔP. From group 1 to group 3, spontaneous indices increased significantly (18.1±1.7 versus 33.3±4.0; 14.4±1.1 versus 25.5±22; 12.9±1.1 versus 20.8±2.0; and 6.4±0.6 versus 16.2±1.4 ms/mm Hg [mean±SEM] for Seq+, Seq−, LFα, and LF
gain
, respectively), with no significant changes afterward. CC and DC were inversely proportional to age (
r
=−0.49 and −0.62, respectively,
P
<0.001). The efficiency of neural integrative mechanisms, estimated as the ratio of spontaneous indices and CC, more than doubled from group 1 to group 3. Spontaneous indices were linearly related to measures of cardiac vagal activity.

Conclusions—

The increase in spontaneous indices from early childhood to adolescence, despite gradual stiffening of the carotid artery, may indicate improved cardiovagal autonomic function, which is most likely a result of maturation of neural mechanisms, attaining peak level at adolescence.
Mesenchymal Stem Cells and the Artery Wall
Authors: Abedin Moeen , Tintut Yin , Demer Linda L.
Published: October 2004

The presence of ectopic tissue in the diseased artery wall is evidence for the presence of multipotential stem cells in the vasculature. Mesenchymal stem cells were first identified in the marrow stroma, and they differentiate along multiple lineages giving rise to cartilage, bone, fat, muscle, and vascular tissue in vitro and in vivo. Transplantation studies show that marrow-derived mesenchymal stem cells appear to enter the circulation and engraft other tissues, including the artery wall, at sites of injury. Recent evidence indicates that mesenchymal stem cells are also present in normal artery wall and microvessels and that they also may enter the circulation, contributing to the population of circulating progenitor cells and engrafting other tissues. Thus, the artery wall is not only a destination but also a source of progenitor cells that have regenerative potential. Although potential artifacts, such as fusion, need to be taken into consideration, these new developments in vascular biology open important therapeutic avenues. A greater understanding of how mesenchymal stem cells from the bone marrow or artery wall bring about vascular regeneration and repair may lead to novel cell-based treatments for cardiovascular disease.
Nuclear Receptor Signaling in the Control of Cholesterol Homeostasis
Authors: Ory Daniel S.
Published: October 2004

Cholesterol is essential for all mammalian cells. Cellular cholesterol requirements are met through de novo synthesis and uptake of plasma lipoproteins, homeostatic responses that are transcriptionally regulated by the sterol regulatory element-binding proteins (SREBPs). To prevent cytotoxicity attributable to accumulation of excess cholesterol, liver X receptors (LXRs) and the farnesoid X receptor (FXR), together with other members of the nuclear receptor superfamily, promote the storage, transport, and catabolism of sterols and their metabolites. Members of this metabolic nuclear receptor family include receptors for oxysterols (LXRs), bile acids (CAR, FXR, and PXR), and fatty acids (PPARs). Through coordinated regulation of transcriptional programs, these nuclear receptors regulate key aspects of cellular and whole-body sterol homeostasis, including cholesterol absorption, lipoprotein synthesis and remodeling, lipoprotein uptake by peripheral tissues, reverse cholesterol transport, and bile acid synthesis and absorption. This review focuses on the nuclear receptors that are central to the lipid metabolic signaling cascades, communication between lipid metabolites and their receptors, and the role of nuclear receptors in orchestrating the complex transcriptional programs that govern cholesterol and bile acid metabolism.
Apurinic/Apyrmidinic Endonuclease 1 Regulates Endothelial NO Production and Vascular Tone
Authors: Jeon Byeong Hwa , Gupta Gaurav , Park Young Chul , Qi Bing , Haile Azeb , Khanday Firdous A. , Liu Yan-Xia , Kim Jin-Man , Ozaki Michitaka , White Anthony R. , Berkowitz Dan E. , Irani Kaikobad
Published: October 2004

The dual-function protein apurinic/apyrmidinic endonuclease/redox factor-1 (APE1/ref-1) is essential for DNA repair and also governs the reductive activation of many redox-sensitive transcription factors. We examined the role of APE1/ref-1 in regulation of endothelium-dependent tone and systemic blood pressure. APE1/ref-1
+/−
mice have impaired endothelium-dependent vasorelaxation, reduced vascular NO levels, and are hypertensive. APE1/ref-1 upregulates H-ras expression and leads to H-ras-mediated, phosphoinositide-3 kinase/Akt kinase-dependent calcium sensitization of endothelial NO synthase (eNOS), stimulating NO production. The reducing property of APE1/ref-1 is essential for upregulation of H-ras and for the calcium sensitization of eNOS. These findings uncover a novel physiological role for APE1/ref-1 in regulating vascular tone by governance of eNOS activity and bioavailable NO.
C-Reactive Protein Enhances LOX-1 Expression in Human Aortic Endothelial Cells
Authors: Li Ling , Roumeliotis Nadia , Sawamura Tatsuya , Renier Geneviève
Published: October 2004

C-reactive protein (CRP), a characteristic inflammatory marker, is a powerful predictor of cardiovascular events. Recent data suggest that CRP may also promote atherogenesis through inducing endothelial dysfunction. Lectin-like oxidized low-density lipoprotein (oxLDL) receptor-1 (LOX-1) is a newly identified endothelial receptor for oxLDL that plays a pivotal role in oxLDL-induced endothelial dysfunction. Whether CRP may regulate endothelial LOX-1 and induce endothelial dysfunction through this receptor is unknown. In the present study, we studied the in vitro effect of CRP on LOX-1 expression in human aortic endothelial cells (HAECs) and the role of LOX-1 in CRP-induced human monocyte adhesion to endothelium and oxLDL uptake by endothelial cells. Incubation of HAECs with CRP enhanced, in a dose- and time-dependent manner, LOX-1 mRNA and protein levels. Induction of LOX-1 protein was already present at 5 μg/mL CRP and reached a maximum at 25 μg/mL. This effect was reduced by antibodies against CD32/CD64, endothelin-1 (ET-1) and interleukin-6 (IL-6). The extent of stimulation of LOX-1 achieved by CRP was comparable to that elicited by high glucose and IL-6 and remained unchanged in presence of these factors. Finally, CRP increased, through LOX-1, both human monocyte adhesion to endothelial cells and oxLDL uptake by these cells. We conclude that CRP enhances endothelial LOX-1 expression and propose a new mechanism by which CRP may promote endothelial dysfunction, that of inducing LOX-1.
Critical Role for Transient Receptor Potential Channel TRPM4 in Myogenic Constriction of Cerebral Arteries
Authors: Earley Scott , Waldron Brian J. , Brayden Joseph E.
Published: October 2004

Local control of cerebral blood flow is regulated in part through myogenic constriction of resistance arteries. Although this response requires Ca
2+
influx via voltage-dependent Ca
2+
channels secondary to smooth muscle cell depolarization, the mechanisms responsible for alteration of vascular smooth muscle (VSM) cell membrane potential are not fully understood. A previous study from our laboratory demonstrated a critical role for a member of the transient receptor potential (TRP) superfamily of ion channels, TRPC6, in this response. Several other of the approximately 22 identified TRP proteins are also present in cerebral arteries, but their functions have not been elucidated. Two of these channels, TRPM4 and TRPM5, exhibit biophysical properties that are consistent with a role for control of membrane potential of excitable cells. We hypothesized that TRPM4/TRPM5-dependent currents contribute to myogenic vasoconstriction of cerebral arteries. Cation channels with unitary conductance, ion selectivity and Ca
2+
-dependence similar to those of cloned TRPM4 and TRPM5 were present in freshly isolated VSM cells. We found that TRPM4 mRNA was detected in both whole cerebral arteries and in isolated VSM cells whereas TRPM5 message was absent from cerebral artery myocytes. We also found that pressure-induced smooth muscle cell depolarization was attenuated in isolated cerebral arteries treated with TRPM4 antisense oligodeoxynucleotides to downregulate channel subunit expression. In agreement with these data, myogenic vasoconstriction of intact cerebral arteries administered TRPM4 antisense was attenuated compared with controls, whereas KCl-induced constriction did not differ between groups. We concluded that activation of TRPM4-dependent currents contributed to myogenic vasoconstriction of cerebral arteries.
Binding of Myosin Binding Protein-C to Myosin Subfragment S2 Affects Contractility Independent of a Tether Mechanism
Authors: Harris Samantha P. , Rostkova Elena , Gautel Mathias , Moss Richard L.
Published: October 2004

Mutations in the cardiac myosin binding protein-C gene (cMyBP-C) are among the most prevalent causes of inherited hypertrophic cardiomyopathy. Although most cMyBP-C mutations cause reading frameshifts that are predicted to encode truncated peptides, it is not known if or how expression of these peptides causes disease. One possibility is that because the N-terminus contains a unique binding site for the S2 subfragment of myosin, shortened cMyBP-C peptides could directly affect myosin contraction by binding to S2. To test this hypothesis, we compared the effects of a C1C2 protein containing the myosin S2 binding site on contractile properties in permeablized myocytes from wild-type and cMyBP-C knockout mice. In wild-type myocytes, the C1C2 protein reversibly increased myofilament Ca
2+
sensitivity of tension, but had no effect on resting tension. Identical results were observed in cMyBP-C knockout myocytes where C1C2 increased Ca
2+
sensitivity of tension with the half-maximal response elicited at ≈5 μmol/L C1C2. Maximum force was not affected by C1C2. However, phosphorylation of C1C2 by cAMP-dependent protein kinase reduced its ability to increase Ca
2+
sensitivity. These results demonstrate that binding of the C1C2 peptide to S2 alone is sufficient to affect myosin contractile function and suggest that regulated binding of cMyBP-C to myosin S2 by phosphorylation directly influences myofilament Ca
2+
sensitivity.
Isolation and Expansion of Adult Cardiac Stem Cells From Human and Murine Heart
Authors: Messina Elisa , De Angelis Luciana , Frati Giacomo , Morrone Stefania , Chimenti Stefano , Fiordaliso Fabio , Salio Monica , Battaglia Massimo , Latronico Michael V.G. , Coletta Marcello , Vivarelli Elisabetta , Frati Luigi , Cossu Giulio , Giacomello Alessandro
Published: October 2004

Cardiac myocytes have been traditionally regarded as terminally differentiated cells that adapt to increased work and compensate for disease exclusively through hypertrophy. However, in the past few years, compelling evidence has accumulated suggesting that the heart has regenerative potential. Recent studies have even surmised the existence of resident cardiac stem cells, endothelial cells generating cardiomyocytes by cell contact or extracardiac progenitors for cardiomyocytes, but these findings are still controversial. We describe the isolation of undifferentiated cells that grow as self-adherent clusters (that we have termed “cardiospheres”) from subcultures of postnatal atrial or ventricular human biopsy specimens and from murine hearts. These cells are clonogenic, express stem and endothelial progenitor cell antigens/markers, and appear to have the properties of adult cardiac stem cells. They are capable of long-term self-renewal and can differentiate in vitro and after ectopic (dorsal subcutaneous connective tissue) or orthotopic (myocardial infarction) transplantation in SCID beige mouse to yield the major specialized cell types of the heart: myocytes (ie, cells demonstrating contractile activity and/or showing cardiomyocyte markers) and vascular cells (ie, cells with endothelial or smooth muscle markers).
Elevated Placental Soluble Vascular Endothelial Growth Factor Receptor-1 Inhibits Angiogenesis in Preeclampsia
Authors: Ahmad Shakil , Ahmed Asif
Published: October 2004

Preeclampsia is an inflammatory disorder in which serum levels of vascular endothelial growth factor (VEGF) and its soluble receptor-1 (sVEGFR-1, also known as sFlt-1) are elevated. We hypothesize that VEGF and placenta growth factor (PlGF) are dysregulated in preeclampsia due to high levels of sVEGFR-1, which leads to impaired placental angiogenesis. Analysis of supernatants taken from preeclamptic placental villous explants showed a four-fold increase in sVEGFR-1 than normal pregnancies, suggesting that villous explants in vitro retain a hypoxia memory reflecting long-term fetal programming. The relative ratios of VEGF to sVEGFR-1 and PlGF to sVEGFR-1 released from explants decreased by 53% and 70%, respectively, in preeclampsia compared with normal pregnancies. Exposure of normal villous explants to hypoxia increased sVEGFR-1 release compared with tissue normoxia (
P
<0.001), as did stimulation with tumor necrosis factor-α (
P
<0.01). Conditioned medium (CM) from normal villous explants induced endothelial cell migration and in vitro tube formation, which were both attenuated by pre-incubation with exogenous sVEGFR-1 (
P
<0.001). In contrast, endothelial cells treated with preeclamptic CM showed substantially reduced angiogenesis compared with normal CM (
P
<0.001), which was not further decreased by the addition of exogenous sVEGFR-1, indicating a saturation of the soluble receptor. Removal of sVEGFR-1 by immunoprecipitation from preeclamptic CM significantly restored migration (
P
<0.001) and tube formation (
P
<0.001) to levels comparable to that induced by normal CM, demonstrating that elevated levels of sVEGFR-1 in preeclampsia are responsible for inhibiting angiogenesis. Our finding demonstrates the dysregulation of the VEGF/PlGF axis in preeclampsia and offers an entirely new therapeutic approach to its treatment.
Evolving Paradigms in Neuroimaging of the Ischemic Penumbra
Authors: Kidwell Chelsea S. , Alger Jeffry R. , Saver Jeffrey L.
Published: October 2004

Identification of the ischemic penumbra in the acute stroke clinical setting is an important goal for stroke researchers and clinicians. Various models for imaging the penumbra with MRI have been proposed, including the pioneering diffusion–perfusion mismatch model and later multivariate approaches. A number of multicenter clinical trials are now under way to test these models and confirm the utility of MRI-based treatment decisions. Present knowledge about MRI visualization of the salvageable penumbra suggests a promising future in which MRI studies are performed routinely in the acute stroke setting and the data provided by these MRI studies assist in individualizing therapeutic decisions and identifying effective therapies that can be delivered at late time points.
White Matter Lesions and Glial Activation in a Novel Mouse Model of Chronic Cerebral Hypoperfusion
Authors: Shibata Masunari , Ohtani Ryo , Ihara Masafumi , Tomimoto Hidekazu
Published: October 2004

Background and Purpose—

Cerebrovascular white matter (WM) lesions are closely associated with cognitive impairment and gait disorders in the elderly. We have successfully established a mouse model of chronic cerebral hypoperfusion that may provide new strategies for the molecular analysis of cerebrovascular WM lesions.

Methods—

Adult C57Bl/6 male mice were subjected to bilateral common carotid artery stenosis (BCAS) using external microcoils with varying inner diameters from 0.16 to 0.22 mm. Cerebral blood flow (CBF) in the frontal cortices was measured by laser-Doppler flowmetry at 2 hours and at 1, 3, 7, 14, and 30 days after BCAS. The brains were then removed and examined at 30 days with histological stains and immunohistochemistry for markers of microglia and astroglia.

Results—

At 2 hours, the CBF values (ratio to the preoperative value) did not change in the 0.22 mm group but decreased significantly to 77.3±13.4% in the 0.20 mm group, 67.3±18.5% in the 0.18 mm group, and 51.4±11.5% in the 0.16 mm group. At day 1, the CBF began to recover in all groups but remained significantly lower until 14 days in comparison to the control group. In the 0.20 mm and 0.18 mm groups, WM lesions occurred after 14 days without any gray matter involvement. These lesions were the most intense in the corpus callosum adjacent to the lateral ventricle but were mild in the anterior commissure and optic tract. In contrast, 4 of 5 mice developed some gray matter changes in the 0.16 mm group. The proliferation of activated microglia and astroglia was observed in the WM beyond 3 days after BCAS.

Conclusions—

WM lesions were successfully induced after chronic cerebral hypoperfusion with relative preservation of the visual pathway. These features in this mouse model are appropriate for cognitive assessment and genetic analysis, and it may provide a powerful tool to understand the pathophysiology of WM lesions.
Impact of Admission Hyperglycemia on Stroke Outcome After Thrombolysis
Authors: Alvarez-Sabín José , Molina Carlos A. , Ribó Marc , Arenillas Juan F. , Montaner Joan , Huertas Rafael , Santamarina Esteban , Rubiera Marta
Published: October 2004

Background and Purpose—

We evaluated the impact of admission hyperglycemia (HG) on stroke outcome in relation to the timing of reperfusion in patients treated with tissue plasminogen activator (tPA).

Methods—

We studied 138 consecutive stroke patients with a documented middle cerebral artery (MCA) occlusion treated with intravenous tPA <3 hours of stroke onset. Serum glucose was determined at baseline before tPA administration. HG was defined as a glucose level >140 mg/dL. National Institutes of Health Stroke Scale (NIHSS) scores were obtained at baseline and 24 hour. Transcranial Doppler monitoring of recanalization was conducted during the first 12 hour of stroke onset. mRS was used to assess outcome at 3 months.

Results—

Median baseline NIHSS score was 17 points. At baseline, 42 (37.3%) patients were hyperglycemic and 96 (62.7%) normoglycemic. Reperfusion was achieved <3 hours of stroke onset in 32 (23%) patients, between 3 to 6 hours in 49 (36%), 6 to 12 hours in 15 (12%), and in 32 (23%) the MCA remained occluded at 12 hours. A logistic regression model revealed that baseline NIHSS score >16 points (odds ratio [OR], 3.32; 95% CI, 2.18 to 24.7;
P
=0.032) and admission glucose level >140 mg/dL (OR, 5.65; 95% CI, 1.97 to 16.18;
P
=0.002) independently predicted poor outcome (modified Rankin scale, 3 to 6) at 3 months. After adjusting by age, stroke severity, site of MCA occlusion, and degree of recanalization, the contribution of HG for poor outcome was higher as shorter the time to reperfusion. The highest odds for poor outcome related to HG corresponded to patients who recanalized <3 hour (OR, 3.1; 95% CI, 1.8 to 14.3;
P
=0.002), as compared with those who recanalized between 3 and 6 hours (OR, 2.1; 95% CI, 1.1 to 16;
P
=0.034) and between 6 to 12 hours (OR, 1.1; 95% CI, 0.7 to 21;
P
=0.43). Moreover, baseline glucose level was negatively correlated (
r
=−0.45;
P
=0.001) with the degree of improvement in the NIHSS score at 24 hours after early (<3 hours) but not after delayed (>3 hours) or no recanalization.

Conclusion—

The impact of admission HG on stroke outcome varies depending on the time to tPA-induced reperfusion. The detrimental effect of acute HG is higher after early than after delayed or no reperfusion. Ultra-early glycemic control before reperfusion may improve the efficacy of thrombolytic therapy.
Estrogen-Like Compounds for Ischemic Neuroprotection
Authors: Simpkins James W. , Yang Shao-Hua , Liu Ran , Perez Evelyn , Cai Zu Yun , Covey Douglas F. , Green Pattie S.
Published: October 2004

We have synthesized a library of estrogen analogues, including enantiomers of estradiol and A-ring substituted estrogens. These compounds have reduced or no binding to either estrogen receptor-α or estrogen receptor-β, exhibit enhanced neuroprotective activity in in vitro models, and are potent in protecting brain tissue from cerebral ischemia/reperfusion injury. These potent, nonfeminizing estrogen analogues are prime candidates for use in stroke neuroprotection.
Immunogenetic Susceptibility of Atherosclerotic Stroke
Authors: DeGraba Thomas J.
Published: October 2004

The understanding of the pathophysiology governing atherosclerosis supports a prominent role for inflammation pathways in plaque initiation and progression that result in stroke and myocardial infarction. Elevated levels of inflammatory markers in the blood, such as C-reactive protein and CD40 ligand/CD40, in concert with increased expression of adhesion molecules, chemokines, cytokines, matrix metalloproteinases (MMP), and inflammatory cells in the plaque, characterize the symptomatic atherothrombotic state. Advances in predictive capabilities of vascular events using a number of these biomarkers are beginning to remodel our clinical practice in the use of medications such as statins and angiotensin receptor blockers for stroke prevention. Although the general inflammatory features of atherosclerosis are becoming widely recognized, factors resulting in individual variability in plaque formation and instability remain poorly defined. Emerging literature points toward several acquired and innate susceptibility factors in the immune pathways that may provide insight into why many plaques rapidly evolve from a “stable” to an “unstable” or symptomatic state. First, exposure of plaque memory T-lymphocytes to infectious or endogenous antigens may result in rapid clonal expansion of T-cell variable β chain subtypes and stimulate macrophages to release MMPs, causing plaque destabilization. The effects of infectious agents can further be influenced by an individual’s major histocompatibility complex class II molecule profiles, which can affect susceptibility to specific organisms. Second, functional polymorphisms of genes that regulate the immune pathway can predispose patients to a more robust inflammatory expression after risk factor exposure. Identification of a susceptibility gene profile and immunologic mediators that promote T-cell activation provides a unique opportunity for early identification of stroke risk and targets for future therapy.
Evidence of Reperfusion Injury, Exacerbated by Thrombolytic Therapy, in Human Focal Brain Ischemia Using a Novel Imaging Marker of Early Blood–Brain Barrier Disruption
Authors: Warach Steven , Latour Lawrence L.
Published: October 2004

Loss of integrity of the blood–brain barrier (BBB) resulting from ischemia and reperfusion is a hypothesized precursor to hemorrhagic transformation (HT) and worse clinical outcome than would be expected from the beneficial effects of reperfusion. We used a novel magnetic resonance imaging marker to characterize early BBB disruption in acute focal brain ischemia and tested associations with reperfusion, HT, and poor outcome (modified Rankin score >2). The BBB disruption was evident as delayed gadolinium enhancement of cerebrospinal fluid space on fluid-attenuated inversion recovery (FLAIR) images and, for convenience, has been termed hyperintense acute reperfusion marker (HARM). HARM was found in 47 of 144 (33%) ischemic stroke patients. Reperfusion was found to be the strongest independent predictor of early BBB disruption (
P
=0.018) in multivariate analysis. HARM was associated with HT and worse clinical outcome (after adjustment for initial severity). It was also associated with more severe strokes at onset and greater age. Because the timing of the disruption was early enough (median estimate 3.8 hours from onset) to make it relevant to acute thrombolytic therapy, early BBB disruption as defined by HARM may be a promising target for adjunctive therapy to reduce the complications associated with thrombolytic therapy, broaden the therapeutic window, and improve clinical outcome.
Angiotensinogen Promoter B-Haplotype Associated With Cerebral Small Vessel Disease Enhances Basal Transcriptional Activity
Authors: Schmidt Helena , Aulchenko Yurii S. , Schweighofer Natascha , Schmidt Reinhold , Frank Sasa , Kostner Gerhard M. , Ott Erwin , van Duijn Cornelia
Published: October 2004

Background and Purpose—

Previously, we described the presence of 5 haplotypes (A to E) at the angiotensinogen (
AGT
) promoter and reported a significant association between the B-haplotype (nucleotide substitutions −6:G→A and −20:A→C compared with the wild-type A-haplotype) and magnetic resonance imaging correlates of cerebral small vessel disease (cSVD). The association was independent of hypertension, suggesting a brain-specific effect of this haplotype. In the current study, we investigated transcriptional activities of the 5 promoter haplotypes in astrocytes, the main source of cerebral
AGT
, and in hepatocytes, the main source of systemic
AGT
, as well as determined the evolutionary relatedness of the promoter haplotypes.

Methods—

Transcriptional activity depending on the haplotypes and the −6:A and −20:C substitutions was measured in transiently transfected A172 and HepG2 cells. We genotyped 5 new single nucleotide polymorphisms (SNPs) at the
AGT
gene and measured linkage disequilibrium (LD) among SNPs and the promoter haplotypes. An evolution-based haplotype tree was constructed.

Results—

The B-haplotype increased transcriptional activity in both cell types. Its effect was stronger in astrocytes than in hepatocytes (2.4±0.09-fold,
P
<0.001 versus 1.6±0.06-fold,
P
=0.014). Importantly, in astrocytes the combination of the −6:A and the −20:C was mandatory for increased activity, whereas in hepatocytes the −20:C on its own was sufficient. Strong LD between the 5 new SNPs and the promoter haplotypes allowed the reconstruction of 9 haplotypes over the
AGT
gene. Cladistic analyses suggest that the B-haplotype represents an ancient promoter variant.

Conclusions—

Combination of the −6:A and −20:C substitutions in the B-haplotype may promote the development of cSVD by enhancing cerebral angiotensinogen expression.