bluuebunny/crossref_metadata_2025 huggingface dataset:
Variability in the sonic muscles of the Lusitanian toadfish (Halobatrachus didactylus): acoustic signals may reflect individual quality
Authors: Amorim M.C.P. , Vasconcelos R. O. , Parreira B.
Published: September 2009

Animal vocalizations are good examples of signals that have been shaped by sexual selection and often contribute to resolve contests or the choice of mates. We relate the mass of the sound-producing muscles of a highly vocal fish species, the Lusitanian toadfish ( Halobatrachus didactylus (Bloch and Schneider, 1801)), with the sender’s physical features, such as body size, and reproductive and body condition. In this species, both sexes are known to emit sounds during agonistic interactions and males rely on their mate attraction vocalizations to reproduce. Sonic muscles were highly variable among males (CV = 40%) and females (CV = 33%) and showed sexual dimorphism. Regression analysis showed that variability in the sonic muscles was best explained by total length and fish condition in males and females. Liver mass in both genders, and the mass of the testes accessory glands, also explained sonic muscle variability. These variables explained 96% and 91% of the sonic muscle mass variability in males and females, respectively. As in teleost fishes sonic muscle mass correlates to particular sound acoustic features, we propose that in the Lusitanian toadfish sounds can inform the receiver about the sender’s quality, such as body size and condition, which are critical information in contests and mate choice.
灣仔區青少年服務需要調查的啟示
Authors: 梁 麗儀 , 李 建賢 , 陳 德茂
Published: September 2009

未提供摘要。
Molecular regulation of cigarette smoke induced-oxidative stress in human retinal pigment epithelial cells: implications for age-related macular degeneration
Authors: Bertram Kurt M. , Baglole Carolyn J. , Phipps Richard P. , Libby Richard T.
Published: September 2009

Cigarette smoke is the most important environmental risk factor for developing age-related macular degeneration (AMD). Damage to the retinal pigment epithelium (RPE) caused by cigarette smoke may underlie the etiology of AMD. This study investigated the molecular and cellular effects of cigarette smoke exposure on human RPE cells. ARPE-19 or primary human RPE cells were exposed to cigarette smoke extract (CSE) or hydroquinone (HQ), a component of cigarette smoke. The effect of this exposure on key aspects of RPE vitality including viability, cell size, mitochondrial membrane potential (ΔΨm), superoxide production, 4-hydroxy-2-nonenal (4-HNE), vascular endothelial growth factor (VEGF), and heme oxygenase-1 (HO-1) expression was determined. Exposure of RPE cells to CSE or HQ caused oxidative damage and apoptosis, characterized by a reduction in cell size and nuclear condensation. Evidence of oxidative damage also included increased lipid peroxidation (4-HNE) and mitochondrial superoxide production, as well as a decrease in intracellular glutathione (GSH). Exogenous administration of antioxidants (GSH and N-acetyl-cysteine) prevented oxidative damage to the RPE cells caused by CSE. Cigarette smoke also induced expression of VEGF, HO-1, and the transcription factor nuclear factor erythroid-derived 2, like 2 (NRF2). However, NRF2 was only modestly involved in CSE-induced HO-1 expression, as shown by the NRF2 small interfering RNA studies. These new findings demonstrate that cigarette smoke is a potent inducer of oxidative damage and cell death in human RPE cells. These data support the hypothesis that cigarette smoke contributes to AMD pathogenesis by causing oxidative damage and cell death to RPE cells.
Chronic oxidative stress sensitizes hepatocytes to death from 4-hydroxynonenal by JNK/c-Jun overactivation
Authors: Singh Rajat , Wang Yongjun , Schattenberg Jörn M. , Xiang Youqing , Czaja Mark J.
Published: September 2009

Sustained activation of the c-Jun NH2-terminal kinase (JNK) signaling pathway mediates the development and progression of experimental diet-induced nonalcoholic fatty liver disease (NAFLD). Delineating the mechanism of JNK overactivation in the setting of a fatty liver is therefore essential to understanding the pathophysiology of NAFLD. Both human and experimental NAFLD are associated with oxidative stress and resultant lipid peroxidation, which have been proposed to mediate the progression of this disease from simple steatosis to steatohepatitis. The ability of oxidants and the lipid peroxidation product 4-hydroxynonenal (HNE) to activate JNK signaling suggested that these two factors may act synergistically to trigger JNK overactivation. The effect of HNE on hepatocyte injury and JNK activation was therefore examined in cells under chronic oxidant stress from overexpression of the prooxidant enzyme cytochrome P450 2E1 (CYP2E1), which occurs in NAFLD. CYP2E1-generated oxidant stress sensitized a rat hepatocyte cell line to death from normally nontoxic concentrations of HNE. CYP2E1-overexpressing cells underwent a more profound depletion of glutathione (GSH) in response to HNE secondary to decreased γ-glutamylcysteine synthetase activity. GSH depletion led to overactivation of JNK/c-Jun signaling at the level of mitogen-activated protein kinase kinase 4 that induced cell death. Oxidant stress and the lipid peroxidation product HNE cause synergistic overactivation of the JNK/c-Jun signaling pathway in hepatocytes, demonstrating that HNE may not be just a passive biomarker of hepatic oxidant stress but rather an active mediator of hepatocellular injury through effects on JNK signaling.
Identification and functional characterization of the intermediate-conductance Ca2+-activated K+ channel (IK-1) in biliary epithelium
Authors: Dutta Amal K. , Khimji Al-karim , Sathe Meghana , Kresge Charles , Parameswara Vinay , Esser Victoria , Rockey Don C. , Feranchak Andrew P.
Published: September 2009

In the liver, adenosine triphosphate (ATP) is an extracellular signaling molecule that is released into bile and stimulates a biliary epithelial cell secretory response via engagement of apical P2 receptors. The molecular identities of the ion channels involved in ATP-mediated secretory responses have not been fully identified. Intermediate-conductance Ca2+-activated K+ channels (IK) have been identified in biliary epithelium, but functional data are lacking. The aim of these studies therefore was to determine the location, function, and regulation of IK channels in biliary epithelial cells and to determine their potential contribution to ATP-stimulated secretion. Expression of IK-1 mRNA was found in both human Mz-Cha-1 biliary cells and polarized normal rat cholangiocyte (NRC) monolayers, and immunostaining revealed membrane localization with a predominant basolateral signal. In single Mz-Cha-1 cells, exposure to ATP activated K+ currents, increasing current density from 1.6 ± 0.1 to 7.6 ± 0.8 pA/pF. Currents were dependent on intracellular Ca2+ and sensitive to clotrimazole and TRAM-34 (specific IK channel inhibitors). Single-channel recording demonstrated that clotrimazole-sensitive K+ currents had a unitary conductance of 46.2 ± 1.5 pS, consistent with IK channels. In separate studies, 1-EBIO (an IK activator) stimulated K+ currents in single cells that were inhibited by clotrimazole. In polarized NRC monolayers, ATP significantly increased transepithelial secretion which was inhibited by clotrimazole. Lastly, ATP-stimulated K+ currents were inhibited by the P2Y receptor antagonist suramin and by the inositol 1,4,5-triphosphate (IP3) receptor inhibitor 2-APB. Together these studies demonstrate that IK channels are present in biliary epithelial cells and contribute to ATP-stimulated secretion through a P2Y-IP3 receptor pathway.
Ranolazine, an antianginal agent, markedly reduces ventricular arrhythmias induced by ischemia and ischemia-reperfusion
Authors: Dhalla Arvinder K. , Wang Wei-Qun , Dow Joan , Shryock John C. , Belardinelli Luiz , Bhandari Anil , Kloner Robert A.
Published: September 2009

We tested the effect of the antianginal agent ranolazine on ventricular arrhythmias in an ischemic model using two protocols. In protocol 1, anesthetized rats received either vehicle or ranolazine (10 mg/kg, iv bolus) and were subjected to 5 min of left coronary artery (LCA) occlusion and 5 min of reperfusion with electrocardiogram and blood pressure monitoring. In p rotocol 2, rats received either vehicle or three doses of ranolazine (iv bolus followed by infusion) and 20 min of LCA occlusion. With protocol 1, ventricular tachycardia (VT) occurred in 9/12 (75%) vehicle-treated rats and 1/11 (9%) ranolazine-treated rats during reperfusion ( P = 0.003). Sustained VT occurred in 5/12 (42%) vehicle-treated but 0/11 in ranolazine-treated rats ( P = 0.037). The median number of episodes of VT during reperfusion in vehicle and ranolazine groups was 5.5 and 0, respectively ( P = 0.0006); median duration of VT was 22.2 and 0 s in vehicle and ranolazine rats, respectively ( P = 0.0006). With p rotocol 2, mortality in the vehicle group was 42 vs. 17% ( P = 0.371), 10% ( P = 0.162) and 0% ( P = 0.0373) with ranolazine at plasma concentrations of 2, 4, and 8 μM, respectively. Ranolazine significantly reduced the incidence of ventricular fibrillation [67% in controls vs. 42% ( P = 0.414), 30% ( P = 0.198) and 8% ( P = 0.0094) in ranolazine at 2, 4, and 8 μM, respectively]. Median number (2.5 vs. 0; P = 0.0431) of sustained VT episodes, incidence of sustained VT (83 vs. 33%, P = 0.0361), and the duration of VT per animal (159 vs. 19 s; P = 0.0410) were also significantly reduced by ranolazine at 8 μM. Ranolazine markedly reduced ischemia-reperfusion induced ventricular arrhythmias. Ranolazine demonstrated promising anti-arrhythmic properties that warrant further investigation.
Nicotinic acetylcholine receptors do not mediate excitatory transmission in young rat carotid body
Authors: Donnelly David F.
Published: September 2009

Carotid body chemoreceptors transduce a decrease in arterial oxygen tension into increased action potential (AP) activity on the sinus nerve, which increases the drive to breathe. The mechanism by which AP activity increases is unresolved, but acetylcholine (ACh), acting through nicotinic receptors, is postulated to be a major contributor to nerve excitation based partly on the demonstration that pharmacological antagonism of nicotinic receptors reduces the afferent nerve response in some studies. However, most previous studies relied on indirect measures of chemoreceptor activity or utilized a recording configuration that is sensitive to AP morphology in addition to AP frequency. In the present study, single-unit AP activity was recorded from the soma of rat chemoreceptor neurons in vitro. The nicotinic blocker mecamylamine (50 μM) ablated the excitatory actions of exogenous ACh and increased, rather than decreased, AP activity during moderate hypoxia. At higher dosage (500 μM) AP height was reduced, conduction velocity slowed, and conduction failure occurred, especially during hypoxia, producing the appearance of a decreased response to hypoxia. Recovery from mecamylamine block was slow (>10 min). In contrast to mecamylamine, suramin, a P2X receptor blocker, reversibly inhibited the response to hypoxia, suggesting relatively free diffusion of drugs to the glomus cell/nerve synaptic site. These results strongly suggest that ACh acting through nicotinic receptors does not mediate excitatory transmission in rat carotid body and that previous results demonstrating such a role may have been partially influenced by changes in AP morphology or conduction failure.
Systemic hypoxia affects exercise-mediated antitumor cytotoxicity of natural killer cells
Authors: Wang Jong-Shyan , Wu Chia-Kuan
Published: September 2009

Natural killer cells (NKs) are important to the clearance of transformed cells. This investigation elucidates how systemic hypoxia influences mobilization of the NK subsets and cytotoxicity of NKs to nasopharyngeal carcinoma cells (NPCs) during exercise. Sixteen sedentary men performed six distinct experimental tests in an air-conditioned normobaric hypoxia chamber: high-intensity exercise [HE; up to maximal O2 consumption (V̇o2 max)] under 21% O2; moderate-intensity exercise (ME; 50% V̇o2 max for 30 min) under 12%, 15%, and 21% O2; and breathing 12% and 15% O2 for 30 min at rest. The results demonstrated that 21% O2 HE, but not ME, increased cellular perforin/granzyme B/interferon-γ levels in NKs and interferon-γ concentration in NK-NPC coincubation, and also promoted capacity of NKs to bind to NPCs and NK-induced CD95 expression and phosphatidylserine exposure of NPCs. However, the HE simultaneously increased percentages of the replicative senescent (CD57+ and CD28−) NKs and the NKs with inhibitory receptors (KLRG1+) that entered the bloodstream from peripheral tissues. Breathing 12% and 15% O2 at rest did not influence mobilization of NK subsets and cytotoxicity of NKs to NPCs. Although both 12% and 15% O2 ME increased NK count, perforin/granzyme B/interferon-γ levels, NK-NPC binding, and NK-induced CD95 expression and apoptosis of NPC, only 12% O2 ME increased percentages of the NKs with CD57+/CD28−/KLRG1+ in blood. Therefore, we conclude that systemic hypoxic exposure affects redistribution of NK subsets and anti-NPC cytotoxicity of NKs during exercise in a concentration-dependent manner. Moreover, exposure to 12% O2 promotes the NK cytotoxicity with mobilizing the replicative senescent/inhibitory NKs into the bloodstream during ME.
Role of PPARs in Radiation-Induced Brain Injury
Authors: Ramanan Sriram , Zhao Weiling , Riddle David R. , Robbins Mike E.
Published: September 2009

Whole-brain irradiation (WBI) represents the primary mode of treatment for brain metastases; about 200 000 patients receive WBI each year in the USA. Up to 50% of adult and 100% of pediatric brain cancer patients who survive >6 months post-WBI will suffer from a progressive, cognitive impairment. At present, there are no proven long-term treatments or preventive strategies for this significant radiation-induced late effect. Recent studies suggest that the pathogenesis of radiation-induced brain injury involves WBI-mediated increases in oxidative stress and/or inflammatory responses in the brain. Therefore, anti-inflammatory strategies can be employed to modulate radiation-induced brain injury. Peroxisomal proliferator-activated receptors (PPARs) are ligand-activated transcription factors that belong to the steroid/thyroid hormone nuclear receptor superfamily. Although traditionally known to play a role in metabolism, increasing evidence suggests a role for PPARs in regulating the response to inflammation and oxidative injury. PPAR agonists have been shown to cross the blood-brain barrier and confer neuroprotection in animal models of CNS disorders such as stroke, multiple sclerosis and Parkinson's disease. However, the role of PPARs in radiation-induced brain injury is unclear. In this manuscript, we review the current knowledge and the emerging insights about the role of PPARs in modulating radiation-induced brain injury.
The TF-603A/G gene promoter polymorphism and circulating monocyte tissue factor gene expression in healthy volunteers
Authors: Reny Jean-Luc , Laurendeau Ingrid , Fontana Pierre , Bièche Ivan , Dupont Annabelle , Remones Véronique , Emmerich Joseph , Vidaud Michel , Aiach Martine , Gaussem Pascale
Published: September 2009

Three single nucleotide polymorphisms (-603A/G, -1322C/T, -1812C/T) and one deletion/insertion polymorphism (-1208D/I) are present in the tissue factor (TF) gene promoter sequence. These polymorphisms are in complete linkage disequilibrium, determining two haplotypes with almost equal frequency. The -603A/-1208D/-1322C/-1812C haplotype, presently defined as TF-603A, has been linked to venous thromboembolic disease, with a potentially protecting effect. The effects of the TF-603A/G gene polymorphism on monocyte gene expression and on a whole-blood clotting time (WBCT) are not known. We determined the WBCT in basal conditions (H0) and after 4 hours of LPS stimulation ex vivo (H4LPS) on blood samples from 100 young healthy caucasian male subjects on 2 visits, 7 days apart. Monocyte TF mRNA was quantified at H0 and H4LPS by real-time quantitative reverse-transcription PCR. The monocyte TF mRNA values determined at the first and second visits were concordant. In H4LPS samples, TF mRNA levels were increased 70-fold. The TF-603A haplotype was associated with 40%-lower TF mRNA levels at H0 (P=0.0002) and this association followed the same trend but was no longer significant at H4LPS. At H4LPS, TF mRNA levels were associated with WBCT shortening (P=0.0003). WBCT at H0 was not concordant over time, precluding any genotype-phenotype analysis. WBCT at H4LPS was concordant over time but was not related to the TF-603A/G polymorphism. The TF-603A/G gene promoter polymorphism thus significantly influences constitutive TF gene expression in human monocytes but has no major effect on TF gene expression or on WBCT in LPS stimulated conditions.
Acipimox, an Inhibitor of Lipolysis, Attenuates Atherogenesis in LDLR-Null Mice Treated With HIV Protease Inhibitor Ritonavir
Authors: Guo Wen , Wong Siu , Pudney Jeffrey , Jasuja Ravi , Hua Ning , Jiang Lan , Miller Andrew , Hruz Paul W. , Hamilton James A. , Bhasin Shalender
Published: September 2009

Objectives—

The advent of HIV protease inhibitors has greatly extended the life span of AIDS patients. With an aging HIV
+
population, the cardiometabolic side effects of these drugs are becoming increasingly important clinical concerns. The purpose of this study was to test the hypothesis that inhibition of adipose lipolysis will retard atherogenic lesion development induced by the antiviral protease inhibitors.

Methods and Results—

LDLR-null mice receiving ritonavir were compared with those receiving ritonavir plus lipolysis inhibitor acipimox or vehicle alone to determine how acipimox would affect ritonavir-induced atherogenesis. Intermittent high-fat high-cholesterol diet was used to facilitate optimal atheromatous lesion development. Drug effects were assessed as changes in aortic lesion score, plasma lipid and lipoprotein profile, body fat mass, and insulin-induced suppression of plasma fatty acid concentrations. Ritonavir increased aortic lesions, in association with decreased body fat mass, impaired antilipolysis action of insulin, and increased proatherogenic plasma lipoproteins. All these adverse effects were attenuated by cotreatment with acipimox.

Conclusions—

Our results provide the first direct evidence that supports the hypothesis that dysregulation of adipose lipolysis is an important contributor to the proatherogenic role of selected HIV protease inhibitors.
Identification and Functional Characterization of Phosphorylation Sites on GTP Cyclohydrolase I
Authors: Du Jianhai , Wei Na , Xu Hao , Ge Ying , Vásquez-Vivar Jeannette , Guan Tongju , Oldham Keith T. , Pritchard Kirkwood A. , Shi Yang
Published: September 2009

Objective—

The posttranslational regulation of GTP cyclohydrolase I (GCH-1), the rate-limiting enzyme for tetrahydrobiopterin (BH4) synthesis, remains elusive. Here, we identified specific phosphorylation sites on GCH-1 and characterized the function of these sites.

Methods and Results—

Mass spectrometry studies showed overexpressed rat GCH-1 was phosphorylated at serine (S) 51, S167, and threonine (T) 231 in HEK293 cells, whereas a computational analysis of GCH-1 revealed 8 potential phosphorylation sites (S51, S72, T85, T91, T103, S130, S167 and T231). GCH-1 activity and BH4 were significantly decreased in cells transfected with the phospho-defective mutants (S72A, T85A, T91A, T103A, or S130A) and increased in cells transfected with the T231A mutant. BH4 and BH2 were increased in cells transfected with S51E, S72E, T85E, T91E, T103D, or T130D mutants, but decreased in cells transfected with the T231D mutant, whereas cells transfected with the S167A or the S167E mutant had increased BH2. Additionally, cells transfected with the T231A mutant had reduced GCH-1 nuclear localization and nuclear GCH-1 activity.

Conclusion—

Our data suggest GCH-1 activity is regulated either positively by phosphorylation S51, S72, T85, T91, T103, and S130, or negatively at T231. Such information might be useful in designing new therapies aiming at improving BH4 bioavailability.
HDL3-Mediated Inactivation of LDL-Associated Phospholipid Hydroperoxides Is Determined by the Redox Status of Apolipoprotein A-I and HDL Particle Surface Lipid Rigidity
Authors: Zerrad-Saadi Amal , Therond Patrice , Chantepie Sandrine , Couturier Martine , Rye Kerry-Anne , Chapman M. John , Kontush Anatol
Published: September 2009

Objectives—

Small dense HDL3 particles of defined lipidome and proteome potently protect atherogenic LDL against free radical-induced oxidation; the molecular determinants of such antioxidative activity in these atheroprotective, antiinflammatory particles remain indeterminate.

Methods and Results—

Formation of redox-active phosphatidylcholine hydroperoxides (PCOOH) and redox-inactive phosphatidylcholine hydroxides (PCOH) was initiated in LDL by free radical-induced oxidation. Human HDL3 inactivated LDL-derived PCOOH (−62%,
P
<0.01) and enhanced accumulation of PCOH (2.1-fold,
P
<0.05); in parallel, HDL3 accumulated minor amounts of PCOOH. Enzyme-deficient reconstituted dense HDL potently inactivated PCOOH (−43%,
P
<0.01). HDL3-mediated reduction of PCOOH to PCOH occurred concomitantly with oxidation of methionine residues in HDL3-apolipoprotein AI (apoAI). Preoxidation of methionine residues by chloramine T markedly attenuated PCOOH inactivation (−35%); by contrast, inhibition of HDL3-associated enzymes was without effect. PCOOH transfer rates from oxidized LDL to phospholipid liposomes progressively decreased with increment in the rigidity of the phospholipid monolayer.

Conclusions—

The redox status of apoAI and surface lipid rigidity represent major determinants of the potent HDL3-mediated protection of LDL against free radical-induced oxidation. Initial transfer of PCOOH to HDL3 is modulated by the surface rigidity of HDL3 particles with subsequent reduction of PCOOH to PCOH by methionine residues of apoAI.
Inhibition of Prolyl Hydroxylase Domain-Containing Protein Suppressed Lipopolysaccharide-Induced TNF-α Expression
Authors: Takeda Kotaro , Ichiki Toshihiro , Narabayashi Eriko , Inanaga Keita , Miyazaki Ryohei , Hashimoto Toru , Matsuura Hirohide , Ikeda Jiro , Miyata Toshio , Sunagawa Kenji
Published: September 2009

Objective—

Prolyl hydroxylase domain-containing proteins (PHDs) play pivotal roles in oxygen-sensing system through the regulation of α-subunit of hypoxia-inducible factor (HIF), a key transcription factor governing a large set of gene expression to adapt hypoxia. Although tissue hypoxia plays an essential role in maintaining inflammation, the role of PHDs in the inflammatory responses has not been clearly determined. Here, we investigated the role of PHDs in lipopolysaccharide (LPS)-induced tumor necrosis factor α (TNF-α) induction in macrophages.

Methods and Results—

Northern blot analysis and ELISA revealed that LPS-induced TNF-α upregulation was strongly suppressed by PHD inhibitors, dimethyloxallyl glycine (DMOG), and TM6008 in RAW264.7 macrophages. DMOG suppressed LPS-induced TNF-α upregulation in HIF-1α–depleted cells and HIF-1α overexpression failed to suppress the induction of TNF-α. DMOG rather suppressed LPS-induced NF-κB transcriptional activity. Downregulation of
Phd1
or
Phd2
mRNA by RNA interference partially attenuated LPS-induced TNF-α induction. DMOG also inhibited LPS-induced TNF-α production in peritoneal macrophages as well as human macrophages.

Conclusions—

PHD inhibition by DMOG or RNA interference inhibited LPS-induced TNF-α upregulation in macrophages possibly through NF-κB inhibition, which is independent of HIF-1α accumulation. This study suggests that PHDs are positive regulators of LPS-induced inflammatory process, and therefore inhibition of PHD may be a novel strategy for the treatment of inflammatory diseases.
Absence of Akt1 Reduces Vascular Smooth Muscle Cell Migration and Survival and Induces Features of Plaque Vulnerability and Cardiac Dysfunction During Atherosclerosis
Authors: Fernández-Hernando Carlos , József Levente , Jenkins Deborah , Di Lorenzo Annarita , Sessa William C.
Published: September 2009

Objective—

Deletion of Akt1 leads to severe atherosclerosis and occlusive coronary artery disease. Vascular smooth muscle cells (VSMCs) are an important component of atherosclerotic plaques, responsible for promoting plaque stability in advanced lesions. Fibrous caps of unstable plaques contain less collagen and ECM components and fewer VSMCs than caps from stable lesions. Here, we investigated the role of Akt1 in VSMC proliferation, migration, and oxidative stress–induced apoptosis. In addition, we also characterized the atherosclerotic plaque morphology and cardiac function in an atherosclerosis-prone mouse model deficient in Akt1.

Methods and Results—

Absence of Akt1 reduces VSMC proliferation and migration. Mechanistically, the proliferation and migratory phenotype found in Akt1-null VSMCs was linked to reduced Rac-1 activity and MMP-2 secretion. Serum starvation and stress-induced apoptosis was enhanced in Akt1 null VSMCs as determined by flow cytometry using Annexin V/PI staining. Immunohistochemical analysis of atherosclerotic plaques from
Akt1

−/−
ApoE
−/−

mice showed a dramatic increase in plaque vulnerability characteristics such as enlarged necrotic core and reduced fibrous cap and collagen content. Finally, we show evidence of myocardial infarcts and cardiac dysfunction in
Akt1

−/−
ApoE
−/−

mice analyzed by immunohistochemistry and echocardiography, respectively.

Conclusion—

Akt1 is essential for VSMC proliferation, migration, and protection against oxidative stress–induced apoptosis. Absence of Akt1 induces features of plaque vulnerability and cardiac dysfunction in a mouse model of atherosclerosis.
Initial Experience of Assessing Esophageal Tissue Injury and Recovery Using Delayed-Enhancement MRI After Atrial Fibrillation Ablation
Authors: Badger Troy J. , Adjei-Poku Yaw A. , Burgon Nathan S. , Kalvaitis Saul , Shaaban Akram , Sommers Daniel N. , Blauer Joshua J.E. , Fish; Eric N. , Akoum Nazem , Haslem Thomas S. , Kholmovski Eugene G. , MacLeod Rob S. , Adler Douglas G. , Marrouche Nassir F.
Published: September 2009

Background—

Esophageal wall thermal injury after atrial fibrillation ablation is a potentially serious complication. However, no noninvasive modality has been used to describe and screen patients to examine whether esophageal wall injury has occurred. We describe a noninvasive method of using delayed-enhancement MRI to detect esophageal wall injury and subsequent recovery after atrial fibrillation ablation.

Methods and Results—

We analyzed the delayed-enhancement MRI scans of 41 patients before ablation and at 24 hours and 3 months after ablation to determine whether there was evidence of contrast enhancement in the esophagus after atrial fibrillation ablation. In patients with contrast enhancement, 3D segmentation of the esophagus was performed using a novel image processing method. Upper gastrointestinal endoscopy was then performed. Repeat delayed-enhancement MRI and upper gastrointestinal endoscopy was performed 1 week later to track changes in lesions. The wall thickness of the anterior and posterior wall of the esophagus was measured at 3 time points: before ablation, 24 hours after ablation, and 3 months after ablation. Evaluation of preablation MRI scans demonstrated no cases of esophageal enhancement. At 24 hours, 5 patients showed contrast enhancement. Three of these patients underwent upper gastrointestinal endoscopy, which demonstrated esophageal lesions. Repeat upper gastrointestinal endoscopy and MRI 1 week later demonstrated resolution of the lesions. All 5 patients had confirmed resolution of enhancement at 3 months. All patients with esophageal tissue enhancement demonstrated left atrial wall enhancement directly adjacent to the regions of anterior wall esophageal enhancement.

Conclusions—

Our preliminary results indicate delayed-enhancement MRI can assess the extent and follow progression of esophageal wall injury after catheter ablation of atrial fibrillation. It appears that acute esophageal injury recovers within 1 week of the procedure.
Transcriptional Upregulation of Mitochondrial Uncoupling Protein 2 Protects Against Oxidative Stress-Associated Neurogenic Hypertension
Authors: Chan Samuel H.H. , Wu Chiung-Ai , Wu Kay L.H. , Ho Ying-Hao , Chang Alice Y.W. , Chan Julie Y.H.
Published: September 2009

Rationale
:

Mitochondrial uncoupling proteins (UCPs) belong to a superfamily of mitochondrial anion transporters that uncouple ATP synthesis from oxidative phosphorylation and mitigates mitochondrial reactive oxygen species production.

Objective
:

We assessed the hypothesis that UCP2 participates in central cardiovascular regulation by maintaining reactive oxygen species homeostasis in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons that maintain vasomotor tone located. We also elucidated the molecular mechanisms that underlie transcriptional upregulation of UCP2 in response to oxidative stress in RVLM.

Methods and Results
:

In Sprague–Dawley rats, transcriptional upregulation of UCP2 in RVLM by rosiglitazone, an activator of its transcription factor peroxisome proliferator-activated receptor (PPAR)γ, reduced mitochondrial hydrogen peroxide level in RVLM and systemic arterial pressure. Oxidative stress induced by microinjection of angiotensin II into RVLM augmented UCP2 mRNA or protein expression in RVLM, which was antagonized by comicroinjection of NADPH oxidase inhibitor (diphenyleneiodonium chloride), superoxide dismutase mimetic (tempol), or p38 mitogen-activated protein kinase inhibitor (SB203580) but not by extracellular signal-regulated kinase 1/2 inhibitor (U0126). Angiotensin II also induced phosphorylation of the PPARγ coactivator, PPARγ coactivator (PGC)-1α, and an increase in formation of PGC-1α/PPARγ complexes in a p38 mitogen-activated protein kinase–dependent manner. Intracerebroventricular infusion of angiotensin II promoted an increase in mitochondrial hydrogen peroxide production in RVLM and chronic pressor response, which was potentiated by gene knockdown of UCP2 but blunted by rosiglitazone.

Conclusions
:

These results suggest that transcriptional upregulation of mitochondrial UCP2 in response to an elevation in superoxide plays an active role in feedback regulation of reactive oxygen species production in RVLM and neurogenic hypertension associated with chronic oxidative stress.
Concurrent Vasculogenesis and Neurogenesis From Adult Neural Stem Cells
Authors: Ii Masaaki , Nishimura Hiromi , Sekiguchi Haruki , Kamei Naosuke , Yokoyama Ayumi , Horii Miki , Asahara Takayuki
Published: September 2009

Rationale
:

Recent reports have demonstrated that signals from vascular endothelial cells are necessary for organogenesis that may precede vasculogenesis. However, the origin of these neovascular cells in regenerating tissue has not been clarified.

Objective
:

Here we tested the hypothesis that adult neural stem cells (NSCs) can differentiate into vascular lineage, as well as neural lineage, in the process of collaborative organogenesis.

Methods and Results
:

NSCs, clonally isolated from mouse brain, were shown to develop endothelial and smooth muscle phenotypes in vitro. To elucidate whether NSCs can simultaneously differentiate into vascular and neural cells in vivo, genetically labeled NSCs were administered to mice with unilateral sciatic nerve crush injury or operatively induced brain and myocardial ischemia. Two weeks later, necropsy examination disclosed recruitment of the labeled NSCs to sites of injury differentiating into vascular cells (endothelial cells and vascular smooth muscle cells) and Schwann cells in regenerating nerve. Similarly, NSC-derived vascular cells/astrocytes and endothelial cells were identified in ischemic brain tissue and capillaries in myocardium 2 weeks following transplantation, respectively.

Conclusions
:

These findings, concurrent vasculogenesis and neurogenesis from a common stem cell, suggest that certain somatic stem cells are capable of differentiating into not only somatic cells of identity but also into vascular cells for tissue regeneration.
Periadventitial Adipose Tissue Plays a Critical Role in Vascular Remodeling
Authors: Takaoka Minoru , Nagata Daisuke , Kihara Shinji , Shimomura Iichiro , Kimura Yu , Tabata Yasuhiko , Saito Yoshihiko , Nagai Ryozo , Sata Masataka
Published: September 2009

Rationale
:

Obesity is associated with a high incidence of cardiovascular complications. However, the molecular link between obesity and vascular disease is not fully understood. Most previous studies have focused on the association between cardiovascular disease and accumulation of visceral fat. Periadventitial fat is distributed ubiquitously around arteries throughout the body.

Objective
:

Here, we investigated the impact of obesity on inflammation in the periadventitial adipose tissue and on lesion formation after vascular injury.

Methods and Results
:

High-fat, high-sucrose feeding induced inflammatory changes and decreased adiponectin expression in the periadventitial adipose tissue, which was associated with enhanced neointima formation after endovascular injury. Removal of periadventitial fat markedly enhanced neointima formation after injury, which was attenuated by transplantation of subcutaneous adipose tissue from mice fed on regular chow. Adiponectin-deficient mice showed markedly enhanced lesion formation, which was reversed by local delivery, but not systemic administration, of recombinant adiponectin to the periadventitial area. The conditioned medium from subcutaneous fat attenuated increased cell number of smooth muscle cells in response to platelet derived growth factor-BB.

Conclusions
:

Our findings suggest that periadventitial fat may protect against neointimal formation after angioplasty under physiological conditions and that inflammatory changes in the periadventitial fat may have a direct role in the pathogenesis of vascular disease accelerated by obesity.
Ultrastructural and Functional Remodeling of the Coupling Between Ca
2+
Influx and Sarcoplasmic Reticulum Ca
2+
Release in Right Atrial Myocytes From Experimental Persistent Atrial Fibrillation
Authors: Lenaerts Ilse , Bito Virginie , Heinzel Frank R. , Driesen Ronald B. , Holemans Patricia , D'hooge Jan , Heidbüchel Hein , Sipido Karin R. , Willems Rik
Published: September 2009

Rationale
:

Persistent atrial fibrillation (AF) has been associated with structural and electric remodeling and reduced contractile function.

Objective
:

To unravel mechanisms underlying reduced sarcoplasmic reticulum (SR) Ca
2+
release in persistent AF.

Methods
:

We studied cell shortening, membrane currents, and [Ca
2+
]
i
in right atrial myocytes isolated from sheep with persistent AF (duration 129±39 days, N=16), compared to matched control animals (N=21). T-tubule density, ryanodine receptor (RyR) distribution, and local [Ca
2+
]
i
transients were examined in confocal imaging.

Results
:

Myocyte shortening and underlying [Ca
2+
]
i
transients were profoundly reduced in AF (by 54.8% and 62%,
P
<0.01). This reduced cell shortening could be corrected by increasing [Ca
2+
]
i
. SR Ca
2+
content was not different. Calculated fractional SR Ca
2+
release was reduced in AF (by 20.6%,
P
<0.05). Peak Ca
2+
current density was modestly decreased (by 23.9%,
P
<0.01). T-tubules were present in the control atrial myocytes at low density and strongly reduced in AF (by 45%,
P
<0.01), whereas the regular distribution of RyR was unchanged. Synchrony of SR Ca
2+
release in AF was significantly reduced with increased areas of delayed Ca
2+
release. Propagation between RyR was unaffected but Ca
2+
release at subsarcolemmal sites was reduced. Rate of Ca
2+
extrusion by Na
+
/Ca
2+
exchanger was increased.

Conclusions
:

In persistent AF, reduced SR Ca
2+
release despite preserved SR Ca
2+
content is a major factor in contractile dysfunction. Fewer Ca
2+
channel–RyR couplings and reduced efficiency of the coupling at subsarcolemmal sites, possibly related to increased Na
+
/Ca
2+
exchanger, underlie the reduction in Ca
2+
release.
Patients With Alzheimer Disease With Multiple Microbleeds
Authors: Goos Jeroen D.C. , Kester M.I. , Barkhof Frederik , Klein Martin , Blankenstein Marinus A. , Scheltens Philip , van der Flier Wiesje M.
Published: September 2009

Background and Purpose—

Microbleeds (MBs) are commonly observed in Alzheimer disease. A minority of patients has multiple MBs. We aimed to investigate associations of multiple MBs in Alzheimer disease with clinical and MRI characteristics and cerebrospinal fluid biomarkers.

Methods—

Patients with Alzheimer disease with multiple (≥8) MBs on T2*-weighted MRI were matched for age, sex, and field strength with patients with Alzheimer disease without MBs on a 1:2 basis. We included 21 patients with multiple MBs (73±7 years, 33% female) and 42 patients without MBs (72±7 years, 38% female). Mini-Mental State Examination was used to assess dementia severity. Cognitive functions were assessed using neuropsychological tests. Medial temporal lobe atrophy (0 to 4), global cortical atrophy (0 to 3), and white matter hyperintensities (0 to 30) were assessed using visual rating scales. In a subset, apolipoprotein E genotype and cerebrospinal fluid amyloid β 1-42, total τ and τ phosphorylated at threonine 181 were determined.

Results—

Patients with multiple MBs performed worse on Mini-Mental State Examination (multiple MB: 17±7; no MB: 22±4,
P
<0.05) despite similar disease duration. Atrophy was not related to presence of MBs, but patients with multiple MBs had more white matter hyperintensities (multiple MB: 8.8±4.8; no MB: 3.2±3.6,
P
<0.05). Adjusted for age, sex, white matter hyperintensities, and medial temporal lobe atrophy, the multiple MB group additionally performed worse on Visual Association Test object naming and animal fluency. Patients with multiple MBs had lower cerebrospinal fluid amyloid β 1-42 levels (307±61) than patients without MBs (505±201,
P
<0.05). Adjusted for the same covariates, total τ, and τ phosphorylated at threonine 181 were higher in the multiple MB group.

Conclusion—

Microbleeds are associated with the clinical manifestation and biochemical hallmarks of Alzheimer disease, suggesting possible involvement of MBs in the pathogenesis of Alzheimer disease.
Diagnosing Delayed Cerebral Ischemia With Different CT Modalities in Patients With Subarachnoid Hemorrhage With Clinical Deterioration
Authors: Dankbaar Jan Willem , de Rooij Nicolien K. , Velthuis Birgitta K. , Frijns Catharina J.M. , Rinkel Gabriel J.E. , van der Schaaf Irene C.
Published: September 2009

Background and Purpose—

Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage worsens the prognosis and is difficult to diagnose. We investigated the diagnostic value of noncontrast CT (NCT), CT perfusion (CTP), and CT angiography (CTA) for DCI after clinical deterioration in patients with subarachnoid hemorrhage.

Methods—

We prospectively enrolled 42 patients with subarachnoid hemorrhage with clinical deterioration suspect for DCI (new focal deficit or Glasgow Coma Scale decrease ≥2 points) within 21 days after hemorrhage. All patients underwent NCT, CTP, and CTA scans on admission and directly after clinical deterioration. The gold standard was the clinical diagnosis DCI made retrospectively by 2 neurologists who interpreted all clinical data, except CTP and CTA, to rule out other causes for the deterioration. Radiologists interpreted NCT and CTP images for signs of ischemia (NCT) or hypoperfusion (CTP) not localized in the neurosurgical trajectory or around intracerebral hematomas, and CTA images for presence of vasospasm. Diagnostic values for DCI of NCT, CTP, and CTA were assessed by calculating sensitivities, specificities, positive predictive values, and negative predictive values with 95% CIs.

Results—

In 3 patients with clinical deterioration, imaging failed due to motion artifacts. Of the remaining 39 patients, 25 had DCI and 14 did not. NCT had a sensitivity of 0.56 (95% CI, 0.37 to 0.73), specificity=0.71 (0.57 to 0.77), positive predictive value=0.78 (0.55 to 0.91), negative predictive value=0.48 (0.28 to 0.68); CTP: sensitivity=0.84 (0.65 to 0.94), specificity=0.79 (0.52 to 0.92), positive predictive value=0.88 (0.69 to 0.96), negative predictive value=0.73 (0.48 to 0.89); CTA: sensitivity=0.64 (0.45 to 0.80), specificity=0.50 (0.27 to 0.73), positive predictive value=0.70 (0.49 to 0.84), negative predictive value=0.44 (0.23 to 0.67).

Conclusion—

As a diagnostic tool for DCI, qualitative assessment of CTP is overall superior to NCT and CTA and could be useful for fast decision-making and guiding treatment.
Cerebral Microbleeds in Ischemic Stroke Patients on Warfarin Treatment
Authors: Orken Dilek Necioglu , Kenangil Gulay , Uysal Ender , Forta Hulki
Published: September 2009

Background and Purpose—

Cerebral microbleeds (CMBs) are known to be indicative of bleeding prone microangiopathy. Little is known about its significance in anticoagulated patients. We aimed to determine the frequency of CMBs in ischemic stroke patients on warfarin treatment.

Methods—

A total of 141 ischemic stroke patients on warfarin therapy were enrolled in this study. One hundred five patients with similar demographic features who do not use warfarin were chosen as controls. We compared vascular risk factors and radiological findings including CMBs and leukoaraiosis between the groups.

Results—

CMBs on gradient-echo MRI (GE-MRI) were found in 31 patients (22%) and 17 controls (16%) and there was not a significant difference between 2 groups (
P
=0.25). Study patients with CMBs were older than patients without CMBs (
P
=0.04) and frequency of leukoaraiosis was significantly higher (
P
=0.008). Mean duration of warfarin treatment was not different between the patients with and without CMBs (
P
=0.83).

Conclusion—

Although patients with CMBs were older and had more leukoaraiosis the impact of warfarin treatment on CMBs is still controversial.
Sonic Hedgehog Regulates Ischemia/Hypoxia-Induced Neural Progenitor Proliferation
Authors: Sims John R. , Lee Sae-Won , Topalkara Kamil , Qiu Jianhua , Xu Jian , Zhou Zhipeng , Moskowitz Michael A.
Published: September 2009

Background and Purpose—

Sonic hedgehog (Shh) protein is required for the maintenance of neural progenitor cells (NPCs) in the embryonic and adult hippocampus. Brain ischemia causes increased proliferation of hippocampal NPCs. We therefore examined whether Shh regulates the increase in proliferation of NPCs after ischemia/hypoxia.

Methods—

Male SV129 mice were exposed to a 20-minute middle cerebral artery occlusion; hippocampi were then analyzed for Shh mRNA and protein expression by real-time polymerase chain reaction, immunoblot, and immunohistochemistry. Primary cell cultures of neurons, astrocytes, and NPCs were exposed to 16 hours of hypoxia (1% O
2
) and analyzed by real-time polymerase chain reaction and immunoblot for Shh expression. Proliferation of NPCs, in vivo and in vitro, was measured by bromodeoxyuridine incorporation.

Results—

Among the cell types examined in vitro, only NPC and neurons increased
Shh
mRNA under hypoxic conditions. Furthermore, hypoxia increased proliferation of NPCs and this proliferation was enhanced by the addition of recombinant Shh or blocked by the pathway-specific inhibitor, cyclopamine. Middle cerebral artery occlusion was associated with a transient 2-fold increase in the mRNA encoding both
Shh
and its transcription factor,
Gli1
, 0.5 days after ischemia. Within the hippocampus, Shh protein was increased approximately 3-fold 3 and 7 days after ischemia and was observed predominantly within cells in the CA3 and hilar regions. Shh was expressed only in mature neurons. In vivo, cyclopamine suppressed ischemia-induced proliferation of subgranular NPCs.

Conclusion—

The Shh pathway plays a role in the proliferation of NPCs induced by ischemia/hypoxia and might participate in injury remodeling.
Imaging Data Reveal a Higher Pediatric Stroke Incidence Than Prior US Estimates
Authors: Agrawal Nidhi , Johnston S. Claiborne , Wu Yvonne W. , Sidney Stephen , Fullerton Heather J.
Published: September 2009

Background and Purpose—

Prior annualized estimates of pediatric ischemic stroke incidence have ranged from 0.54 to 1.2 per 100 000 US children but relied purely on diagnostic code searches to identify cases. We sought to obtain a new estimate using both diagnostic code searches and searches of radiology reports and to assess the relative value of these 2 strategies.

Methods—

Using the population of 2.3 million children (<20 years old) enrolled in a Northern Californian managed care plan (1993 to 2003), we performed electronic searches of (1) inpatient and outpatient diagnoses for
International Classification of Diseases, 9th Revision
codes suggestive of stroke and cerebral palsy; and (2) radiology reports for key words suggestive of infarction. Cases were confirmed through chart review. We calculated sensitivities and positive predictive values for the 2 search strategies.

Results—

We identified 1307 potential cases from the
International Classification of Diseases, 9th Revision
code search and 510 from the radiology search. A total of 205 ischemic stroke cases were confirmed, yielding an ischemic stroke incidence of 2.4 per 100 000 person-years. The radiology search had a higher sensitivity (83%) than the
International Classification of Diseases, 9th Revision
code search (39%), although both had low positive predictive values. For perinatal stroke, the sensitivity of the stroke
International Classification of Diseases, 9th Revision
codes alone was 12% versus 57% for stroke and cerebral palsy codes combined; the radiology search was again the most sensitive (87%).

Conclusions—

Our incidence estimate doubles that of prior US reports, a difference at least partially explained by our use of radiology searches for case identification. Studies relying purely on
International Classification of Diseases, 9th Revision
code searches may underestimate childhood ischemic stroke rates, particularly for neonates.
Mean, Variance, and Autocorrelation of Subthreshold Potential Fluctuations Driven by Filtered Conductance Shot Noise
Authors: Wolff Lars , Lindner Benjamin
Published: September 2009

We study the subthreshold voltage fluctuations of a conductance-based passive point neuron stimulated by filtered Poissonian shot noise. We give exact analytical expressions in terms of quadratures for the first two time-dependent moments and the autocorrelation function of the membrane voltage. We also derive simplified expressions for the moments in terms of elementary functions that hold true in the limit case of short filter time, small spike amplitude, and a single synaptic reversal potential. By means of these expressions, we show that for an ensemble of equilibrated conductances but sharp initial voltage (corresponding to a short voltage clamp at the initial time), the mean and the standard deviation can display nonmonotonic time courses. In particular, transient changes in the standard deviation disagree strongly with the predictions of the commonly used effective time constant approximation over a large parameter range. We also study the dependence of the correlation time of the voltage on the synaptic spike amplitude and the synaptic input rate. All results are confirmed by extensive stochastic simulations.