bluuebunny/crossref_metadata_2025 huggingface dataset:
TIME SERIES INTERVENTION ANALYSIS WITH APPLICATION TO MULTI-UNIT SYSTEM MAINTENANCE MANAGEMENT
Authors: OKOGBAA O. GEOFFREY , PENG XIA , SAMPATH VIJAYALAKSHMI
Published: September 2004

Maintenance management is important in order for complex systems to continue operation with minimal interruption. A primary concern of maintenance management is the failure pattern exhibited by increasing failure rate (IFR) systems. In the existent literature, a common assumption about component behavior is that after replacement the new components work "as good as new". In this study, we relax this assumption and employ intervention analysis based on time series formulation to study the failure behavior of the system under preventive/predictive maintenance policies. We explicitly consider different preventive maintenance and replacement policies, the aging characteristics of the units as well as other operational issues. The proposed methodology provides the basis for a new approach to the vexing problem of the realistic characterization of IFR systems in the presence of maintenance intervention. The model is verified using data collected from a real life system and the parameter estimation is carried out using the refined instrumental variables method.
TEST PLAN ALLOCATION TO MINIMIZE SYSTEM RELIABILITY ESTIMATION VARIABILITY
Authors: RAMIREZ-MARQUEZ JOSE E. , COIT DAVID W. , JIN TONGDAN
Published: September 2004

A new methodology is presented to allocate testing units to the different components within a system when the system configuration is fixed and there are budgetary constraints limiting the amount of testing. The objective is to allocate additional testing units so that the variance of the system reliability estimate, at the conclusion of testing, will be minimized. Testing at the component-level decreases the variance of the component reliability estimate, which then decreases the system reliability estimate variance. The difficulty is to decide which components to test given the system-level implications of component reliability estimation. The results are enlightening because the components that most directly affect the system reliability estimation variance are often not those components with the highest initial uncertainty. The approach presented here can be applied to any system structure that can be decomposed into a series-parallel or parallel-series system with independent component reliability estimates. It is demonstrated using a series-parallel system as an example. The planned testing is to be allocated and conducted iteratively in distinct sequential testing runs so that the component and system reliability estimates improve as the overall testing progresses. For each run, a nonlinear programming problem must be solved based on the results of all previous runs. The testing allocation process is demonstrated on two examples.
TRADE AND THE ENVIRONMENT: ECONOMIC AND ENVIRONMENTAL IMPACTS OF GLOBAL DAIRY TRADE LIBERALISATION
Authors: SAUNDERS CAROLINE , CAGATAY SELIM
Published: September 2004

This paper presents a partial equilibrium model of dairy sector international trade which has been extended to include physical dairy production systems and their effect on water quality. This combined model, LTEM (Lincoln Trade and Environment Model), is then used to simulate the effects of liberalisation policies on trade flows, dairy production systems and groundwater nitrate levels across different countries. The results show expected variation in price and production impacts, but also varying effects on groundwater quality between and within countries. More specifically, whilst liberalisation lowers dairy production in the EU and reduces the EU nitrate pollution slightly, the balancing production increases elsewhere lead to marginally higher pollution in other countries. This is of policy relevance given contemporary debates about the likely net environmental effect of further trade liberalisation.
POTENTIALS AND RISKS OF BENCHMARKING
Authors: DE BRUIJN HANS , VAN WENDEL DE JOODE RUBEN , VAN DER VOORT HAIKO
Published: September 2004

This article aims to explore some potentials and risks of benchmarking in environmental assessment. The dominant image derived from theory and empirical data is that benchmark tests tend to be based on quantitative measures, which, under certain conditions, produces perverse effects and bureaucracy.

The answer to the central question — Can benchmarks be useful in environmental assessment? — is affirmative. The problem, however, is that due to an inherent characteristic of environmental issues, using quantitative measures will create perverse effects and bureaucracy thus reducing their effectiveness. This article proposes the formulation of rules of the game to increase the effectiveness of benchmarking. These rules are mutual agreements that regulate for instance who are allowed to use and interpret the figures.
REVIEW OF ECOLOGICAL INPUT IN PRELIMINARY EIAS FOR COASTAL RESORT DEVELOPMENT PROJECTS IN MALAYSIA
Authors: VUN LEONG-WAN , LATIFF ABDUL , NORDIN MOHD
Published: September 2004

In Malaysia, environmental impact assessment (EIA) has been mandatory since 1988 as a proactive tool in environmental management for 19 prescribed activities. Since ecological information is an important component in EIA, this study examined the quality of ecological input in 41 preliminary EIAs for coastal resort development. Twelve criteria relating to ecological data, impact prediction, evaluation of impact significance, mitigating measures, residual impacts, monitoring, communication of the report and consultants were reviewed. Results revealed that only 27 percent of the EIAs were found to be satisfactory, whereas the others were at borderline or poor. In describing the existing environment, the majority of the reports made no mention of the survey methods, some of the data included were found to be not site-specific and up-to-date, and the sources of the secondary data presented in these reports were mostly not quoted. There was a tendency to survey terrestrial habitats more than aquatic, and higher plants are surveyed more than animals. Most of the reports also failed to mention the species status although comprehensive lists of species were present. They also failed to quantify the species present in the impacted areas which could lead to inadequate ecological impact prediction. The study also showed that, though all the reports contained a section on ecology, not all the EIA consultants involved in preparing these reports comprised of a multidisciplinary team that has an ecologist/biologist or environmental scientist.
KEYWORDS SPECIFICATION FOR IMAGES USING SANDGLASS-TYPE NEURAL NETWORKS
Authors: ITO SEIJI , OMATU SIGERU
Published: September 2004

We propose a keyword specification method for images, which can be used to retrieve an image by a keyword. In order to specify a keyword for a sub-region of the image, images are segmented in some regions. Here, we consider ten keywords to specify the regions. The image segmentation method consists of the maximum-distance algorithm, labeling, and merging the small regions. We provide training regions for each keyword. Important features of the keyword are selected using the Factor Analysis (FA). The features are compressed into a two-dimensional space using a Sandglass-type Neural Network (SNN). We train the SNN using the training dataset. Then 60 samples of the testing dataset are evaluated by keywords extraction.
Release of ATP from retinal pigment epithelial cells involves both CFTR and vesicular transport
Authors: Reigada David , Mitchell Claire H.
Published: September 2004

The retinal pigment epithelium (RPE) faces the photoreceptor outer segments and regulates the composition of the interstitial subretinal space. ATP enhances fluid movement from the subretinal space across the RPE. RPE cells can themselves release ATP, but the mechanisms and polarity of this release are unknown. The RPE expresses the cystic fibrosis transmembrane conductance regulator (CFTR), and CFTR is associated with ATP release in other epithelial cells. However, an increasing number of reports have suggested that the exocytotic pathway contributes to release. In the present study, we examined the involvement of CFTR and the vesicular pathway in ATP release from RPE cells. Release from cultured human ARPE-19 cells and across the apical membrane of fresh bovine RPE cells in an eyecup was studied. A cAMP cocktail to activate CFTR triggered ATP release from fresh and cultured RPE cells. Release from both RPE preparations was largely prevented by the broad-acting blocker glibenclamide and the specific thiazolidinone CFTR inhibitor CFTR-172. The block by CFTR-172 was enhanced by preincubation and prevented ATP release with 3.5 μM IC50. The rise in intracellular Ca2+ accompanying hypotonic challenge was prevented by CFTR-172. The vesicular transport inhibitor brefeldin A prevented ATP release after stimulation with both hypotonic and cAMP conditions, suggesting vesicular insertion was also involved. These results show an intimate involvement of CFTR in ATP release from RPE cells which can autostimulate receptors on the apical membrane to modify Ca2+ signaling. The requirement for both CFTR and vesicular transport pathways suggests vesicular insertion of CFTR may underlie the release of ATP.
Nitric oxide regulation of myocardial O2consumption and HEP metabolism
Authors: Zhang Jianyi , Gong Guangrong , Ye Yun , Guo Tao , Mansoor Abdul , Hu Qingsong , Ochiai Koichi , Liu Jingbo , Wang Xiaohong , Cheng Yarong , Iverson Nicole , Lee Joseph , From Arthur H. L. , Ugurbil Kamil , Bache Robert J.
Published: September 2004

NO and O2compete at cytochrome- c oxidase, thus potentially allowing NO to modulate mitochondrial respiration. We previously observed a decrease of myocardial phosphocreatine (PCr)/ATP during very high cardiac work states, corresponding to an increase in cytosolic free ADP. This study tested the hypothesis that NO inhibition of respiration contributes to this increase of ADP. Infusion of dobutamine + dopamine (DbDp, each 20 μg·kg−1·min−1iv) to more than double myocardial oxygen consumption (MV̇o2) in open-chest dogs caused a decrease of myocardial PCr/ATP measured with31P NMR from 2.04 ± 0.09 to 1.85 ± 0.08 ( P < 0.05). Inhibition of NO synthesis with Nω-nitro-l-arginine (l-NNA), while catecholamine infusion continued, caused PCr/ATP to increase to the control value. In a second group of animals, l-NNA administered before catecholamine stimulation (reverse intervention of the first group) increased PCr/ATP during basal conditions. In these animals l-NNA did not prevent a decrease of PCr/ATP at the high cardiac work state but, relative to MV̇o2, PCr/ATP was significantly higher after l-NNA. In a third group of animals, pharmacological coronary vasodilation with carbochromen was used to prevent changes in coronary flow that might alter endothelial NO production. In these animals l-NNA again restored depressed myocardial PCr/ATP during catecholamine infusion. The finding that inhibition of NO production increased PCr/ATP suggests that during very high work states NO inhibition of mitochondrial respiration requires ADP to increase to drive oxidative phosphorylation.
Acidosis attenuates P2X purinergic vasoconstriction in skeletal muscle arteries
Authors: Kluess Heidi A. , Buckwalter John B. , Hamann Jason J. , Clifford Philip S.
Published: September 2004

Vasoconstriction via α2-receptors is known to be sensitive to acidic pH, but little is known about the pH sensitivity of P2X receptors. ATP is a cotransmitter released with norepinephrine from the sympathetic nerves and causes vasoconstriction via P2X purinergic receptors on vascular smooth muscle. We hypothesized that reductions in pH would attenuate P2X-mediated vasoconstriction in iliofemoral artery rings. Twenty-five rats were killed, and the iliac and femoral arteries were dissected out and placed in modified Krebs-Henseleit buffer. The arteries were cut into 2-mm sections and mounted in an organ tissue bath. Tension (g) was measured during a potassium chloride and norepinephrine challenge (maximal tension). The arteries were then exposed to α,β-methylene ATP (10−7-10−3 M; n = 13) or phenylephrine (10−7-10−4 M; n = 6) with a tissue bath pH of 7.8, 7.4, and 7.0. Dose-response curves were fit with nonlinear regression analysis to calculate the EC50 and slope. The peak tension with α,β-methylene ATP was lower during pH 7.0 (1.37 ± 0.09 g) compared with pH 7.8 (1.90 ± 0.12 g). EC50 was highest with pH 7.4 (−5.38 ± 0.18 log M α,β-methylene ATP) and lowest with pH 7.0 (−4.9 ± 0.10 log M α,β-methylene ATP). The slopes of the dose-response curves were not different. Pyridoxal phosphate-6-azo(benzene-2,4-disulfonic acid) abolished contraction caused by the addition of α,β-methylene ATP ( n = 6). There was no effect of pH on phenylephrine dose-response curves. These data indicate that the vasoconstrictor response to α,β-methylene ATP is sensitive to pH and that lower pH attenuates the response of P2X purinergic receptors.
Role of endogenous testosterone in myocardial proinflammatory and proapoptotic signaling after acute ischemia-reperfusion
Authors: Wang Meijing , Tsai Ben M. , Kher Ajay , Baker Lauren B. , Wairiuko G. Mathenge , Meldrum Daniel R.
Published: September 2004

Myocardial ischemia is the leading cause of death in both men and women; however, very little information exists regarding the effect of testosterone on the response of myocardium to acute ischemic injury. We hypothesized that testosterone may exert deleterious effects on myocardial inflammatory cytokine production, p38 MAPK activation, apoptotic signaling, and myocardial functional recovery after acute ischemia-reperfusion (I/R). To study this, isolated, perfused rat hearts (Langendorff) from adult males, castrated males, and males treated with a testosterone receptor blocker (flutamide) were subjected to 25 min of ischemia followed by 40 min of reperfusion. Myocardial contractile function (left ventricular developed pressure, left ventricular end-diastolic pressure, positive and negative first derivative of pressure) was continuously recorded. After reperfusion, hearts were analyzed for expression of tissue TNF-α, IL-1β, and IL-6 (ELISA) and activation of p38 MAPK, caspase-1, caspase-3, caspase-11, and Bcl-2 (Western blot). All indices of postischemic myocardial functional recovery were significantly higher in castrated males or flutamide-treated males compared with untreated males. After I/R, castrated male and flutamide-treated male hearts had decreased TNF-α, IL-1β, and IL-6; decreased activated p38 MAPK; decreased caspase-1, caspase-3, and caspase-11; and increased Bcl-2 expression compared with untreated males. These results show that blocking the testosterone receptor (flutamide) or depleting testosterone (castration) in normal males improves myocardial function after I/R. These effects may be attributed to the proinflammatory and/or the proapoptotic properties of endogenous testosterone. Further understanding may allow therapeutic manipulation of sex hormone signaling mechanisms in the treatment of acute I/R.
cAMP phosphodiesterase inhibitors potentiate effects of prostacyclin analogs in hypoxic pulmonary vascular remodeling
Authors: Phillips Peter G. , Long Lu , Wilkins Martin R. , Morrell Nicholas W.
Published: September 2004

We investigated the effects of prostacyclin analogs and isoform-selective phosphodiesterase (PDE) inhibitors, alone and in combination, on pulmonary vascular remodeling in vitro and in vivo. Vascular smooth muscle cells (VSMC) isolated from pulmonary (proximal and distal) and systemic circulations demonstrated subtle variations in expression of PDE isoform mRNA. However, using biochemical assays, we found PDE3 and PDE4 isoforms to be responsible for the majority of cAMP hydrolysis in all VSMC. In growth assays, the prostacyclin analogs cicaprost and iloprost inhibited mitogen-induced proliferation of VSMC in a cAMP-dependent manner. In addition, isoform-selective antagonists of PDEs 1, 3, or 4 inhibited VSMC proliferation, an effect that synergized with the effect of prostacyclin analogs. The inhibitory effects were greater in cells isolated from pulmonary circulation. In an in situ perfused rat lung preparation, administration of prostacyclin analogs or the PDE inhibitors vinpocetine (PDE1), cilostamide (PDE3), or rolipram (PDE4), but not EHNA (PDE2), attenuated acute hypoxic vasoconstriction (HPV). Combinations of agents led to a greater reduction in HPV. Furthermore, during exposure to hypoxia for 13 days, Wistar rats were treated with iloprost, rolipram, cilostamide, or combinations of these agents. Compared with normoxic controls, hypoxic animals developed pulmonary hypertension and distal pulmonary artery muscularization. These parameters were attenuated by iloprost+cilostamide, iloprost+rolipram, and cilostamide+rolipram but were not significantly affected by single agents. Together, these findings provide a greater understanding of the role of cAMP PDEs in VSMC proliferation and provide rationale for combined use of prostacylcin analogs plus PDE3/4 inhibitors in treatment of pulmonary vascular remodeling.
Mitochondrial enzyme content in the muscles of high-performance fish: evolution and variation among fiber types
Authors: Dalziel Anne C. , Moore Shannon E. , Moyes Christopher D.
Published: September 2004

Muscle mitochondrial content varies widely among fiber types and species. We investigated the origins of variation in the activity of the mitochondrial enzyme citrate synthase (CS), an index of mitochondrial abundance, among fiber types and species of high-performance fish (tunas and billfishes). CS activities varied up to 30-fold among muscles: lowest in billfish white muscle and highest in billfish heater organ. Among species, CS activities of red, white, and cardiac muscles of three tuna species were twofold greater than the homologous muscles of two billfish species. Because comparisons of CS amino acid sequences deduced from a combination of PCR methods argue against clade-specific differences in catalytic properties, CS activity reflects CS content among these five species. To assess the bases of these differences in CS activity, we looked at the relationship between CS activity (U/g muscle), nuclear content (DNA/g muscle), and CS transcript levels (CS mRNA/g RNA). Muscle CS activity differed by 10- to 30-fold when expressed per gram of muscle but only threefold when expressed per milligram of DNA. Thus it is nuclear DNA content, not fiber-type differences, in CS gene expression that may be the main determinant of CS activity in muscle. Conversely, evolutionary (tunas vs. billfishes) differences in CS arise from differences in posttranscriptional regulation, based on relationships between CS enzyme levels and CS mRNA assessed by quantitative competitive RT-PCR. These data argue that fiber-type differences can arise without major differences in fiber-type-specific regulation of the CS gene, whereas evolutionary differences may be largely due to posttranscriptional regulation.
Prenatal programming of hypernatremia and hypertension in neonatal lambs
Authors: Ross Michael G. , Desai Mina , Guerra Catalina , Wang Shengbiao
Published: September 2004

Maternal water restriction and the accompanying dehydration-induced anorexia may induce long-term physiological changes in offspring. We determined the impact of prenatal hypertonicity (Pre-Dehy) on offspring cardiovascular and osmoregulatory function. Pre-Dehy lambs were exposed to in utero hypernatremia (8- to 10-meq increase; 110–150 days of gestation) induced by maternal water restriction. Control lambs were born to ewes provided ad libitum water and food throughout gestation. After delivery, all ewes were provided ad libitum water and all newborns were allowed ad libitum nursing. Lambs were prepared with vascular and bladder catheters at 15 ± 2 days of age and studied at 21 ± 2 days. After a 2-h basal period, lambs received an infusion of hypotonic (0.075 M) NaCl (0.15 ml·kg−1·h−1 iv) for 2 h. Lamb arterial blood pressure was monitored, and blood samples were obtained before, during, and after infusion. During the neonatal basal period, Pre-Dehy lambs had significantly increased plasma osmolality (302 ± 1 vs. 294 ± 1 mosmol/kgH2O, P < 0.01), sodium levels (144 ± 1 vs. 140 ± 1 meq/l, P < 0.01), hematocrit (28 ± 1% vs. 25 ± 1%, P < 0.05), and mean arterial blood pressure (79 ± 2 vs. 68 ± 1 mmHg, P < 0.001) compared with control lambs. Despite the infusion of hypotonic saline, Pre-Dehy lambs maintained relative hypertonicity, hypernatremia, and hypertension. However, plasma arginine vasopressin, glomerular filtration rate, and urinary osmolar and sodium excretion and clearance (per kg body wt) were similar in the groups. Offspring of prenatally water-restricted ewes exhibit hypernatremia, hypertonicity, and hypertension, which persist despite hypotonic saline infusion. In utero hypertonicity and perhaps maternal nutrient stress may program offspring osmoregulation and systemic arterial hypertension.
Aberrant expression of myosin isoforms in skeletal muscles from mice lacking therev-erbAαorphan receptor gene
Authors: Pircher P. , Chomez P. , Yu F. , Vennström B. , Larsson L.
Published: September 2004

The rev-erbAα orphan protein belongs to the steroid nuclear receptor superfamily. No ligand has been identified for this protein, and little is known of its function in development or physiology. In this study, we focus on 1) the distribution of the rev-erbAα protein in adult fast- and slow-twitch skeletal muscles and muscle fibers and 2) how the rev-erbAα protein influences myosin heavy chain (MyHC) isoform expression in mice heterozygous (+/−) and homozygous (−/−) for a rev-erbAα protein null allele. In the fast-twitch extensor digitorum longus muscle, rev-erbAα protein expression was linked to muscle fiber type; however, MyHC isoform expression did not differ between wild-type, +/−, or −/− mice. In the slow-twitch soleus muscle, the link between rev-erbAα protein and MyHC isoform expression was more complex than in the extensor digitorum longus. Here, a significantly higher relative amount of the β/slow (type I) MyHC isoform was observed in both rev-erbAα −/− and +/− mice vs. that shown in wild-type controls. A role for the ratio of thyroid hormone receptor proteins α1to α2in modulating MyHC isoform expression can be ruled out because no differences were seen in MyHC isoform expression between thyroid hormone receptor α2-deficient mice (heterozygous and homozygous) and wild-type mice. Therefore, our data are compatible with the rev-erbAα protein playing an important role in the regulation of skeletal muscle MyHC isoform expression.
Angiotensin II early regulated genes in H295R human adrenocortical cells
Authors: Romero Damian G. , Plonczynski Maria , Vergara Gaston R. , Gomez-Sanchez Elise P. , Gomez-Sanchez Celso E.
Published: September 2004

Evidence for the dysregulation of aldosterone synthesis in cardiovascular pathophysiology has renewed interest in the control of its production. Cellular mechanisms by which angiotensin II (ANG II) stimulates aldosterone synthesis in the adrenal zona glomerulosa are incompletely understood. To elucidate the mechanism of intracellular signaling by ANG II stimulation in the adrenal, we have studied immediate-early regulated genes in human adrenal H295R cells using cDNA microarrays. H295R cells were stimulated with ANG II for 3 h. Gene expression was analyzed by microarray technology and validated by real-time RT-PCR. Eleven genes were found to be upregulated by ANG II. These encode the proteins for ferredoxin, Nor1, Nurr1, c6orf37, CAT-1, A20, MBLL, M-Ras, RhoB, GADD45α, and a novel protein designated FLJ45273 . Maximum expression levels for all genes occurred 3–6 h after ANG II stimulation. This increase was dose dependent and preceded maximal aldosterone production. Other aldosterone secretagogues, K+and endothelin-1 (ET-1), also induced the expression of these genes with variable efficiency depending on the gene and with lower potency than ANG II. ACTH had negligible effect on gene expression except for the CAT-1 and Nurr1 genes. These ANG II-stimulated genes are involved in several cellular functions and are good candidate effectors and regulators of ANG II-mediated effects in adrenal zona glomerulosa.
Blockade of the Interaction Between PD-1 and PD-L1 Accelerates Graft Arterial Disease in Cardiac Allografts
Authors: Koga Noritaka , Suzuki Jun-ichi , Kosuge Hisanori , Haraguchi Go , Onai Yasuyuki , Futamatsu Hideki , Maejima Yasuhiro , Gotoh Ryo , Saiki Hitoshi , Tsushima Fumihiko , Azuma Miyuki , Isobe Mitsuaki
Published: September 2004

Background—

Programmed death-1 (PD-1), a member of the CD28 family, has been identified. PD-1 is involved in the negative regulation of some immune responses. We evaluated the role of PD-ligand 1 (PD-L1) in graft arterial disease (GAD) of cardiac allografts and in smooth muscle cells (SMCs).

Methods and Results—

C57BL/6 murine hearts were transplanted into B6.C-H2KhEg mice for examination of GAD. PD-L1 was expressed in SMCs of the thickened intima in the graft coronary arteries, and administration of anti–PD-L1 monoclonal antibody (mAb) enhanced the progression of GAD (luminal occlusion: 55±5.0% versus 9.8±4.3%,
P
<0.05). The expressions of interferon γ (IFN-γ) and tumor necrosis factor α of cardiac allografts were upregulated in response to anti–PD-L1 mAb treatment. In vitro, PD-L1 expression was induced in SMCs in response to IFN-γ stimulation. Sensitized splenocytes increased SMC proliferation, and anti–PD-L1 mAb in combination with IFN-γ stimulation increased this proliferation.

Conclusions—

The PD-L1 pathway regulates both the proliferation of SMCs and GAD. Thus, control of this interaction is a promising strategy for suppression of GAD.
Carvedilol Inhibits Tumor Necrosis Factor-α–Induced Endothelial Transcription Factor Activation, Adhesion Molecule Expression, and Adhesiveness to Human Mononuclear Cells
Authors: Chen Jaw-Wen , Lin Feng-Yen , Chen Yung-Hsiang , Wu Tao-Cheng , Chen Yuh-Lien , Lin Shing-Jong
Published: September 2004

Objective—

We tested the hypothesis that carvedilol, a β-adrenoceptor and α-adrenoceptor antagonist with potent antioxidant property, could inhibit tumor necrosis factor-α (TNF-α)–induced endothelial adhesiveness to human mononuclear cells (MNCs), an early sign of atherogenesis.

Methods and Results—

Circulating MNCs were isolated from the peripheral blood of healthy subjects. Compared with control condition, pretreatment of carvedilol (10 μmol/L for 18 hours) or probucol (5 μmol/L for 18 hours), but not propanolol, prazosin, or both propanolol and prazosin significantly decreased TNF-α–stimulated adhesiveness of cultured human aortic endothelial cells (HAECs) to MNCs. Carvedilol inhibited TNF-α–stimulated endothelial vascular cell adhesion molecule-1 (VCAM-1) and E-selectin (66.0±2.0% and 55.60±1.0% of control,
P
<0.05, respectively) expression, whereas probucol inhibited only VCAM-1 expression (79.0±5.0% of control,
P
<0.05). Propanolol, prazosin, or both did not alter the expression of adhesion molecules. Further, pretreatment with carvedilol significantly inhibited TNF-α–stimulated intracellular reactive oxygen species (ROS) production and the activation of redox sensitive nuclear factor kappa B and activator protein-1 transcription pathways.

Conclusions—

Carvedilol reduced TNF-α–stimulated endothelial adhesiveness to human MNCs by inhibiting intracellular ROS production, transcription factor activation, and VCAM-1 as well as E-selectin expression, suggesting its potential role in clinical atherosclerosis disease.
Reactive Oxygen Species
Authors: Krötz Florian , Sohn Hae-Young , Pohl Ulrich
Published: September 2004

Platelets participate not only in thrombus formation but also in the regulation of vessel tone, the development of atherosclerosis, angiogenesis, and in neointima formation after vessel wall injury. It is not surprising, therefore, that the platelet activation cascade (including receptor-mediated tethering to the endothelium, rolling, firm adhesion, aggregation, and thrombus formation) is tightly regulated. In addition to already well-defined platelet regulatory factors, such as nitric oxide (NO), prostacyclin (PGI
2
), and adenosine, reactive oxygen species (ROS) participate in the regulation of platelet activation. Although exogenously derived ROS are known to affect the regulation of platelet activation, recent data suggest that the platelets themselves generate ROS. Intracellular ROS signaling in activated platelets could be of significant relevance after transient platelet contact with the vessel wall, during the recruitment of additional platelets, and in thrombus formation. This review discusses the potential cellular and enzymatic sources of ROS in platelets, their molecular mechanisms of action in platelet activation, and summarizes in vitro and in vivo evidence for their physiological and potential therapeutic relevance.
Angiotensin II Amplifies Macrophage-Driven Atherosclerosis
Authors: Nobuhiko Ayabe , Suganuma Eisuke , Babaev Vladimir R. , Fogo Agnes , Swift Larry L. , Linton MacRae F. , Fazio Sergio , Ichikawa Iekuni , Kon Valentina
Published: September 2004

Objective—

We evaluated the role of angiotensin II (AII) in a marrow-derived macrophage-driven model of atherosclerosis.

Methods and Results—

Eight-week-old C57BL/6 wild-type mice were reconstituted with bone marrow harvested from apolipoprotein E-deficient (apoE−/−→ apoE+/+) or wild-type for apoE gene (apoE+/+→ apoE+/+) mice. At 20 weeks, mice were exposed to either AII (1000 ng/kg per minute subcutaneously) or saline for 2 weeks. Animals did not differ in body weight, blood pressure, cholesterol/triglycerides, or peripheral blood monocyte counts. ApoE−/−→ apoE+/+ mice exposed to AII had 3-fold greater atherosclerotic area than saline-treated apoE−/−→ apoE+/+ mice. By contrast, AII did not affect atherosclerosis in apoE+/+→ apoE+/+ mice. Macrophage-positive areas were increased by AII in mice reconstituted with either apoE-deficient or apoE-competent marrow. AII also significantly increased fragmentation of elastin laminae in both apoE−/−→ apoE+/+ and apoE+/+→ apoE+/+ mice. In vitro, AII caused greater increase in monocyte chemoattractant protein-1–stimulated migration of macrophages harvested from AII-infused versus saline-infused mice.

Conclusions—

The current studies reveal that AII has both initiating and sustaining proatherogenic effects. By promoting macrophage migration into the vascular intima, AII is pivotal in initiating atherosclerosis; by promoting elastin breaks, a novel mechanism implicated in migration and proliferation of smooth muscle cells, AII may be pivotal in subsequent development and expansion of atherosclerotic lesion.
Sustained β
1
-Adrenergic Stimulation Modulates Cardiac Contractility by Ca
2+
/Calmodulin Kinase Signaling Pathway
Authors: Wang Wang , Zhu Weizhong , Wang Shiqiang , Yang Dongmei , Crow Michael T. , Xiao Rui-Ping , Cheng Heping
Published: September 2004

A tenet of β
1
-adrenergic receptor (β
1
AR) signaling is that stimulation of the receptor activates the adenylate cyclase-cAMP-protein kinase A (PKA) pathway, resulting in positive inotropic and relaxant effects in the heart. However, recent studies have suggested the involvement of Ca
2+
/calmodulin-dependent protein kinase II (CaMKII) in β
1
AR-stimulated cardiac apoptosis. In this study, we determined roles of CaMKII and PKA in sustained versus short-term β
1
AR modulation of excitation-contraction (E-C) coupling in cardiac myocytes. Short-term (10-minute) and sustained (24-hour) β
1
AR stimulation with norepinephrine similarly enhanced cell contraction and Ca
2+
transients, in contrast to anticipated receptor desensitization. More importantly, the sustained responses were largely PKA-independent, and were sensitive to specific CaMKII inhibitors or adenoviral expression of a dominant-negative CaMKII mutant. Biochemical assays revealed that a progressive and persistent CaMKII activation was associated with a rapid desensitization of the cAMP/PKA signaling. Concomitantly, phosphorylation of phospholamban, an SR Ca
2+
cycling regulatory protein, was shifted from its PKA site (
16
Ser) to CaMKII site (
17
Thr). Thus, β
1
AR stimulation activates dual signaling pathways mediated by cAMP/PKA and CaMKII, the former undergoing desensitization and the latter exhibiting sensitization. This finding may bear important etiological and therapeutical ramifications in understanding β
1
AR signaling in chronic heart failure.
Atherosclerosis of Cerebral Arteries in Alzheimer Disease
Authors: Roher Alex E. , Esh Chera , Rahman Afroza , Kokjohn Tyler A. , Beach Thomas G.
Published: September 2004

A growing body of evidence suggests that vascular disease underlies Alzheimer dementia. Atherosclerotic lesions in the circle of Willis and large leptomeningeal vessels were quantified and found to correlate with Alzheimer disease (AD) clinical diagnosis and neuropathology. We hypothesize that AD pathology is the complex end result of slowly evolving vascular disease and parenchymal lesions. Confirmation of a central role for vascular pathology in AD will suggest important treatment options and directions for additional interventions to stave off this dementia.
Effects of Statins on Endothelium and Signaling Mechanisms
Authors: Endres Matthias , Laufs Ulrich
Published: September 2004

Endothelium dysfunction may result from increased production of reactive oxygen species and decreased availability of nitric oxide. Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (ie, statins) exert cholesterol-independent vasoprotective effects that are mediated, in part, through the inhibition of small G-proteins Rho and Rac. Rho negatively regulates endothelial nitric oxide synthase and Rac contributes to NAD(P)H-oxidase activation and superoxide production. Statins inhibit both Rho and Rac GTPase activity via inhibition of geranylgeranylation, which confers endothelial nitric oxide synthase upregulation and decreases superoxide production, respectively. Sudden discontinuation of statin therapy may have negative effects. Withdrawal of statin treatment leads to an overshoot activation of Rho and Rac with dramatic effects on nitric oxide bioavailability, NAD(P)H-oxidase activity, and superoxide production.
Endotoxin Preconditioning Prevents Cellular Inflammatory Response During Ischemic Neuroprotection in Mice
Authors: Rosenzweig Holly L. , Lessov Nikola S. , Henshall David C. , Minami Manabu , Simon Roger P. , Stenzel-Poore Mary P.
Published: September 2004

Background and Purpose—

Tolerance to ischemic brain injury is induced by several preconditioning stimuli, including lipopolysaccharide (LPS). A small dose of LPS given systemically confers ischemic protection in the brain, a process that appears to involve activation of an inflammatory response before ischemia. We postulated that LPS preconditioning modulates the cellular inflammatory response after cerebral ischemia, resulting in neuroprotection.

Methods—

Mice were treated with LPS (0.2 mg/kg) 48 hours before ischemia induced by transient middle cerebral artery occlusion (MCAO). The infarct was measured by 2,3,5-triphenyltetrazolium chloride staining. Microglia/macrophage responses after MCAO were assessed by immunofluorescence and flow cytometry. The effect of MCAO on white blood cells in the brain and peripheral circulation was measured by flow cytometry 48 hours after MCAO.

Results—

LPS preconditioning induced significant neuroprotection against MCAO. Administration of low-dose LPS before MCAO prevented the cellular inflammatory response in the brain and blood. Specifically, LPS preconditioning suppressed neutrophil infiltration into the brain and microglia/macrophage activation in the ischemic hemisphere, which was paralleled by suppressed monocyte activation in the peripheral blood.

Conclusions—

LPS preconditioning induces neuroprotection against ischemic brain injury in a mouse model of stroke. LPS preconditioning suppresses the cellular inflammatory response to ischemia in the brain and circulation. Diminished activation of cellular inflammatory responses that ordinarily exacerbate ischemic injury may contribute to neuroprotection induced by LPS preconditioning.
A novel therapeutic approach for thrombocytopenia by minibody agonist of the thrombopoietin receptor
Authors: Orita Tetsuro , Tsunoda Hiroyuki , Yabuta Naohiro , Nakano Kiyotaka , Yoshino Takeshi , Hirata Yuichi , Ohtomo Toshihiko , Nezu Jun-ichi , Sakumoto Hirofumi , Ono Kouichiro , Saito Mikiyoshi , Kumagai Eiji , Nanami Masahiko , Kaneko Akihisa , Yoshikubo Takashi , Tsuchiya Masayuki
Published: September 2004

Antibodies have brought valuable therapeutics in the clinical treatment of various diseases without serious adverse effects through their intrinsic features such as specific binding to the target antigen with high affinity, clinical safety as serum proteins, and long half-life. Agonist antibodies, furthermore, could be expected to maximize the value of therapeutic antibodies. Indeed, several IgG/IgM antibodies have been reported to induce cellular growth/differentiation and apoptosis. These agonist antibodies, however, should be further improved to exert more potent biologic activities and appropriate serum half-life depending upon the disease indications. Here, we report that IgG antibodies against the thrombopoietin receptor (Mpl), which have an absence or very weak agonist activity, can be engineered to be agonist minibodies, which include diabody or sc(Fv)2 as potent as natural ligand. Through this technological development, minibodies have been successfully constructed to bind and activate 2 types of dysfunctional mutant Mpls that cause congenital amegakaryocytic thrombocytopenia (CAMT). This drastic conversion of biologic activities by designing minibodies can be widely applicable to generate agonist minibodies for clinical application, which will constitute a new paradigm in antibody-based therapeutics.
Extracellular phosphorylation converts pigment epithelium–derived factor from a neurotrophic to an antiangiogenic factor
Authors: Maik-Rachline Galia , Shaltiel Shmuel , Seger Rony
Published: September 2004

The pigment epithelium–derived factor (PEDF) belongs to the superfamily of serine protease inhibitors (serpin). There have been 2 distinct functions attributed to this factor, which can act either as a neurotrophic or as an antiangiogenic factor. Besides its localization in the eye, PEDF was recently reported to be present also in human plasma. We found that PEDF purified from plasma is a phosphoprotein, which is extracellularly phosphorylated by protein kinase CK2 (CK2) and to a lesser degree, intracellularly, by protein kinase A (PKA). CK2 phosphorylates PEDF on 2 main residues, Ser24 and Ser114, and PKA phosphorylates PEDF on one residue only, Ser227. The physiologic relevance of these phosphorylations was determined using phosphorylation site mutants. We found that both CK2 and PKA phosphorylations of PEDF markedly affect its physiologic function. The fully CK2 phosphorylation site mutant S24, 114E abolished PEDF neurotrophic activity but enhanced its antiangiogenic activity, while the PKA phosphorylation site mutant S227E reduced PEDF antiangiogenic activity. This is a novel role of extracellular phosphorylation that is shown here to completely change the nature of PEDF from a neutrophic to an antiangiogenic factor.
Donor-derived IL-15 is critical for acute allogeneic graft-versus-host disease
Authors: Blaser Bradley W. , Roychowdhury Sameek , Kim Daniel J. , Schwind Noah R. , Bhatt Darshna , Yuan Weifeng , Kusewitt Donna F. , Ferketich Amy K. , Caligiuri Michael A. , Guimond Martin
Published: September 2004

Interleukin-15 (IL-15) is a pleiotropic proinflammatory cytokine with inefficient posttranscriptional processing. We hypothesized that endogenous IL-15 could affect disease progression in the well-described C57Bl/6 (B6) → (C57Bl/6 × DBA/2) F1 hybrid (B6D2F1) murine model of acute allogeneic graft-versus-host disease (GVHD). B6D2F1 allogeneic recipients received transplants of IL-15-/- B6 bone marrow cells or B6 bone marrow cells expressing a murine IL-15 transgene (IL-15 tg) modified for efficient translation and secretion. Mice that received transplants of IL-15-/- B6 bone marrow cells displayed a significantly longer median survival time (MST) compared with mice that received transplants of wild-type (wt) B6 bone marrow; in contrast, mice that received transplants of IL-15 tg B6 bone marrow cells had a dramatically decreased MST. This decrease in survival was associated with a substantial activation and expansion of effector-memory (CD44highCD62Llow) CD8+ T lymphocytes. Finally, in vivo depletion of either CD4+ or CD8+ T lymphocyte subsets significantly prolonged survival in mice receiving IL-15 tg B6 marrow, while depletion of both CD4+ and CD8+ T cells provided complete protection from acute GVHD. We thus show that acute GVHD is attenuated in the absence of donor bone marrow–derived IL-15 and conclude that donor-derived IL-15 is a critical mediator of T-cell function in acute GVHD.
Regulation of vascular endothelial barrier function by Epac, a cAMP-activated exchange factor for Rap GTPase
Authors: Cullere Xavier , Shaw Sunil K. , Andersson Lorna , Hirahashi Junichi , Luscinskas Francis W. , Mayadas Tanya N.
Published: September 2004

Endothelial cell-cell junctional proteins and cortical actin are of central importance for regulating vascular permeability. Rap1, a member of the Ras family of GTPases, is enriched at endothelial cell-cell contacts and activated by cyclic AMP (cAMP) through a PKA-independent pathway. Activation of a cAMP-inducible guanine-exchange factor for Rap, Epac, results in markedly enhanced basal endothelial barrier function by increasing cortical actin and subsequent redistribution of adherens and tight junctional molecules to cell-cell contacts. Activation of Epac also counteracts thrombin-induced hyperpermeability through down-regulation of Rho GTPase activation, suggesting cross-talk between Rap and Rho GT-Pases. Thus, Epac/Rap activation represents a new pathway for regulating endothelial cell barrier function.
Cord blood CD4+CD25+-derived T regulatory cell lines express FoxP3 protein and manifest potent suppressor function
Authors: Godfrey Wayne R. , Spoden Darrin J. , Ge Ying G. , Baker Seth R. , Liu Baoling , Levine Bruce L. , June Carl H. , Blazar Bruce R. , Porter Stephen B.
Published: September 2004

CD4+CD25+ T regulatory (Treg) cells have been shown to critically regulate self and allograft tolerance in mice. Studies of human Treg cells have been hindered by low numbers present in peripheral blood and difficult purification. We found that cord blood was a superior source for Treg-cell isolation and cell line generation compared with adult blood. Cord blood CD4+CD25+ cells were readily purified and generated cell lines that consistently exhibited potent suppressor activity, with more than 95% suppression of allogeneic mixed lymphocyte reactions (MLRs) (29 of 30 donors). Cultured Treg cells blocked cytokine accumulation in MLRs, with a less robust inhibition of chemokine production. These cell lines uniformly expressed CD25, CD62L, CCR7, CD27, and intracellular cytotoxic T-lymphocyte antigen-4 (CTLA4). FoxP3 protein, but not mRNA, was specifically expressed. Upon restimulation with anti-CD3/CD28 beads, the cultured Treg cells produced minimal cytokines (interleukin-2 [IL-2], interferon-γ [IFN-γ], and IL-10) and preferentially expressed tumor growth factor-β (TGF-β) latency associated protein. Cytokine production, however, was restored to normal levels by restimulation with phorbol myristate acetate (PMA)/ionomycin. Cord blood–derived cultured suppressor cell function was predominantly independent of IL-10 and TGF-β. These results demonstrate cord blood contains a significant number of Treg precursor cells capable of potent suppressor function after culture activation. Banked cord blood specimens may serve as a readily available source of Treg cells for immunotherapy.
FLT3 inhibition selectively kills childhood acute lymphoblastic leukemia cells with high levels of FLT3 expression
Authors: Brown Patrick , Levis Mark , Shurtleff Sheila , Campana Dario , Downing James , Small Donald
Published: September 2004

FMS-like tyrosine kinase 3 (FLT3) is almost universally expressed in B-precursor childhood acute lymphoblastic leukemia (ALL). Cases of ALL with MLL gene rearrangements and those with high hyperdiploidy (> 50 chromosomes) express the highest levels of FLT3, and activating mutations of FLT3 occur in 18% of MLL-rearranged and 28% of hyperdiploid ALL cases. We determined the antileukemic activity of CEP-701, a potent and selective FLT3 inhibitor, in 8 ALL cell lines and 39 bone marrow samples obtained at diagnosis from infants and children with various subtypes of ALL. CEP-701 induced pronounced apoptotic responses in a higher percentage of samples that expressed high levels of FLT3 (74%, n = 23) compared with samples with low levels of expression (8%, n = 13; P = .0003). Sensitivity to FLT3 inhibition was particularly high in samples with MLL gene rearrangements (82%, n = 11; P = .0005), high hyperdiploidy (100%, n = 5; P = .0007), and/or FLT3 mutations (100%, n = 4; P = .0021). Seven of 7 sensitive samples examined by immunoblotting demonstrated constitutively phosphorylated FLT3 that was potently inhibited by CEP-701, whereas 0 of 6 resistant samples expressed constitutively phosphorylated FLT3. We conclude that the FLT3 inhibitor CEP-701 effectively suppresses FLT3-driven leukemic cell survival. Clinical testing of CEP-701 as a novel molecularly targeted agent for the treatment of childhood ALL is warranted.
Transcriptional regulation of vascular endothelial cell responses to hypoxia by HIF-1
Authors: Manalo Dominador J. , Rowan Ashley , Lavoie Tera , Natarajan Lakshmi , Kelly Brian D. , Ye Shui Q. , Garcia Joe G. N. , Semenza Gregg L.
Published: September 2004

Hypoxia-inducible factor 1 (HIF-1) activates transcription of genes encoding angiogenic growth factors, which are secreted by hypoxic cells and stimulate endothelial cells, leading to angiogenesis. To determine whether HIF-1 also mediates cell-autonomous responses to hypoxia, we have compared gene expression profiles in arterial endothelial cells cultured under nonhypoxic versus hypoxic conditions and in nonhypoxic cells infected with adenovirus encoding beta-galactosidase versus a constitutively active form of HIF-1α (AdCA5). There were 245 gene probes that showed at least 1.5-fold increase in expression in response to hypoxia and in response to AdCA5; 325 gene probes showed at least 1.5-fold decrease in expression in response to hypoxia and in response to AdCA5. The largest category of genes down-regulated by both hypoxia and AdCA5 encoded proteins involved in cell growth/proliferation. Many genes up-regulated by both hypoxia and AdCA5 encoded cytokines/growth factors, receptors, and other signaling proteins. Transcription factors accounted for the largest group of HIF-1–regulated genes, indicating that HIF-1 controls a network of transcriptional responses to hypoxia in endothelial cells. Infection of endothelial cells with AdCA5 under nonhypoxic conditions was sufficient to induce increased basement membrane invasion and tube formation similar to the responses induced by hypoxia, indicating that HIF-1 mediates cell-autonomous activation of endothelial cells.