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ABSTRACT: This article presents an overview of systems engineering and describes common core principles found in systems engineering methodologies. The Patient Care Program Acute Care Initiative collaboration between the Armstrong Institute of the Johns Hopkins School of Medicine and the Gordon and Betty Moore Foundation, which will use systems engineering to reduce patient harm in the intensive care unit, is introduced. Specific examples of applying a systems engineering approach to the Patient Care Program Acute Care Initiative are presented.
Critical care clinics 01/2013; 29(1):113-24. · 1.72 Impact Factor
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ABSTRACT: It is postulated that inhibition of cytosolic phospholipase A(2) alpha (cPLA(2)α) can reduce severity of stroke injury. This is supported by the finding that cPLA(2)α-deficient mice are partially protected from transient, focal cerebral ischemia. The object of this study was to determine the effect of cPLA(2)α inhibition with arachidonyl trifluoromethyl ketone (ATK) on stroke injury in mice. Male C57BL/6 mice were subjected to 1h of focal cerebral ischemia followed by 24 or 72 h of reperfusion. Mice were treated with ATK or vehicle by intermittent intraperitoneal injection or continuous infusion via an implanted infusion pump. ATK injections 1h before and then 1 and 6h after the start of reperfusion significantly reduced infarction volumes in striatum and hemisphere after 24h of reperfusion. ATK did not reduce injury if it was not administered before onset of ischemia or was not administered after 6h of reperfusion. Intermittent doses of ATK failed to reduce infarct volume after 72 h of reperfusion. Continuous infusion with ATK throughout 72h of reperfusion significantly reduced cortical and whole hemispheric infarct volume compared to vehicle treatment. Following ischemia and reperfusion, ATK treatment significantly reduced brain PLA(2) activity. These results are the first to demonstrate a therapeutic effect of cPLA(2)α inhibition on ischemia and reperfusion injury and define a therapeutic time window. cPLA(2)α activity augments injury in the acute and delayed phases of cerebral ischemia and reperfusion injury. We conclude that cPLA(2)α inhibition may be clinically useful if started before initiation of cerebral ischemia.
Brain research 07/2012; 1471:129-37. · 2.46 Impact Factor
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ABSTRACT: The aim of this study was to evaluate whether a nocturnal telemedicine service improves culture, staff satisfaction, and perceptions of quality of care in a highly staffed university critical care system.
We conducted an experiment to determine the effect of telemedicine on nursing-staff satisfaction and perceptions of the quality of care in an intensive care unit (ICU). We surveyed ICU nurses using a modified version of a previously validated tool before deployment and after a 2-month experimental program of tele-ICU. Nurses in another, similar ICU within the same hospital academic medical center served as concurrent controls for the survey responses.
Survey responses were measured using a 5-point Likert scale, and results were analyzed using paired t testing. Survey responses of the nurses in the intervention ICU (n = 27) improved significantly after implementation of the tele-ICU program in the relations and communication subscale (2.99 ± 1.13 pre vs 3.27 ± 1.27 post, P < .01), the psychological working conditions and burnout subscale (3.10 ± 1.10 pre vs 3.23 ± 1.11 post, P < .02), and the education subscale (3.52 ± 0.84 pre vs 3.76 ± 0.78 post, P < .03). In contrast, responses in the control ICU (n = 11) declined in the patient care and perceived effectiveness (3.94 ± 0.80 pre vs 3.48 ± 0.86 post, P < .01) and the education (3.95 ± 0.39 pre vs 3.50 ± 0.80 post, P < .05) subscales.
Telemedicine has the potential to improve staff satisfaction and communication in highly staffed ICUs.
Journal of critical care 03/2012; 27(4):426.e9-16. · 2.13 Impact Factor
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ABSTRACT: Functional hyperemia of the cerebral vascular system matches regional blood flow to the metabolic demands of the brain. One current model of neurovascular control holds that glutamate released by neurons activates group I metabotropic glutamate receptors (mGluRs) on astrocytes, resulting in the production of diffusible messengers that act to regulate smooth muscle cells surrounding cerebral arterioles. The acute mouse brain slice is an experimental system in which changes in arteriole diameter can precisely measured with light microscopy. Stimulation of the brain slice triggers specific cellular responses that can be correlated to changes in arteriole diameter. Here we used inositol trisphosphate receptor type 2 (IP(3)R2) and cytosolic phospholipase A(2) alpha (cPLA(2)α) deficient mice to determine if astrocyte mGluR activation coupled to IP(3)R2-mediated Ca(2+) release and subsequent cPLA(2)α activation is required for arteriole regulation. We measured changes in astrocyte cytosolic free Ca(2+) and arteriole diameters in response to mGluR agonist or electrical field stimulation in acute neocortical mouse brain slices maintained in 95% or 20% O(2). Astrocyte Ca(2+) and arteriole responses to mGluR activation were absent in IP(3)R2(-/-) slices. Astrocyte Ca(2+) responses to mGluR activation were unchanged by deletion of cPLA(2)α but arteriole responses to either mGluR agonist or electrical stimulation were ablated. The valence of changes in arteriole diameter (dilation/constriction) was dependent upon both stimulus and O(2) concentration. Neuron-derived NO and activation of the group I mGluRs are required for responses to electrical stimulation. These findings indicate that an mGluR/IP(3)R2/cPLA(2)α signaling cascade in astrocytes is required to transduce neuronal glutamate release into arteriole responses.
PLoS ONE 01/2012; 7(8):e42194. · 4.09 Impact Factor
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ABSTRACT: Group B Streptococcus (GBS) is the most common bacterium causing neonatal meningitis, and neonatal GBS meningitis continues to be an important cause of mortality and morbidity. Here we provide the first direct evidence that host cytosolic phospholipase A₂α (cPLA₂α) contributes to type III GBS invasion of human brain microvascular endothelial cells (HBMEC), which constitute the blood-brain barrier and penetration into the brain, the key step required for the development of GBS meningitis. This was shown by our demonstration that pharmacological inhibition and gene deletion of cPLA₂α significantly decreased GBS invasion of the HBMEC monolayer and penetration into the brain. cPLA₂α releases arachidonic acid from membrane phospholipids, and we showed that the contribution of cPLA₂α to GBS invasion of HBMEC involved lipoxygenated metabolites of arachidonic acid, cysteinyl leukotrienes (LTs). In addition, type III GBS invasion of the HBMEC monolayer involves protein kinase Cα (PKCα), as shown by time-dependent PKCα activation in response to GBS as well as decreased GBS invasion in HBMEC expressing dominant-negative PKCα. PKCα activation in response to GBS, however, was abolished by inhibition of cPLA₂α and cysteinyl LTs, suggesting that cPLA₂α and cysteinyl LTs contribute to type III GBS invasion of the HBMEC monolayer via PKCα. These findings demonstrate that specific host factors involving cPLA₂α and cysteinyl LTs contribute to type III GBS penetration of the blood-brain barrier and their contribution involves PKCα.
Infection and immunity 08/2011; 79(10):4088-93. · 4.21 Impact Factor
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ABSTRACT: Escherichia coli K1 meningitis occurs following penetration of the blood-brain barrier, but the underlying mechanisms involved in E. coli penetration of the blood-brain barrier remain incompletely understood. We have previously shown that host cytosolic phospholipase A(2)α (cPLA(2)α) contributes to E. coli invasion of human brain microvascular endothelial cells (HBMEC), which constitute the blood-brain barrier, but the underlying mechanisms remain unclear. cPLA(2)α selectively liberates arachidonic acid from membrane phospholipids. Here, we provide the first direct evidence that host 5-lipoxygenase and lipoxygenase products of arachidonic acid, cysteinyl leukotrienes (LTs), contribute to E. coli K1 invasion of HBMEC and penetration into the brain, and their contributions involve protein kinase C alpha (PKCα). These findings demonstrate that arachidonic acid metabolism regulates E. coli penetration of the blood-brain barrier, and studies are needed to further elucidate the mechanisms involved with metabolic products of arachidonic acid for their contribution to E. coli invasion of the blood-brain barrier.
Infection and immunity 10/2010; 78(10):4302-10. · 4.21 Impact Factor
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ABSTRACT: Subspecialization of critical care units and overall increasing demand for critical care services has led to inefficiencies in allocation of critical care resources with potential impacts on hospital economics and patient outcomes. Centralized management of critical care resource allocation within an institution may improve use while simultaneously ensuring quality of patient care. The authors' institution has implemented a Central Intensivist Physician (CIP) program to oversee resource allocation within the adult surgical intensive care units (ICUs). The result has been an improvement in patient flow throughout the surgical ICUs manifested by steady case cancellation rates despite increasing acuity and length of stay. Additionally, triage duties have been shifted from the individual unit physician to the CIP, resulting in improved provider satisfaction from improved continuity of rounds. The authors conclude that the CIP program may improve overall critical care resource use while maintaining unit specialization within a large tertiary care hospital setting.
American Journal of Medical Quality 05/2010; 25(5):343-5. · 1.64 Impact Factor
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ABSTRACT: The enzyme cytosolic phospholipase A2 alpha (cPLA2alpha) has been implicated in the progression of cerebral injury following ischemia and reperfusion. Previous studies in rodents suggest that cPLA2alpha enhances delayed injury extension and disruption of the blood brain barrier many hours after reperfusion. In this study we investigated the role of cPLA2alpha in early ischemic cerebral injury.
Middle cerebral artery occlusion (MCAO) was performed on cPLA2alpha+/+ and cPLA2alpha-/- mice for 2 hours followed by 0, 2, or 6 hours of reperfusion. The levels of cPLA2alpha, cyclooxygenase-2, neuronal morphology and reactive oxygen species in the ischemic and contralateral hemispheres were evaluated by light and fluorescent microscopy. PGE2 content was compared between genotypes and hemispheres after MCAO and MCAO and 6 hours reperfusion. Regional cerebral blood flow was measured during MCAO and phosphorylation of relevant MAPKs in brain protein homogenates was measured by Western analysis after 6 hours of reperfusion.
Neuronal cPLA2alpha protein increased by 2-fold immediately after MCAO and returned to pre-MCAO levels after 2 hours reperfusion. Neuronal cyclooxygenase-2 induction and PGE2 concentration were greater in cPLA2alpha+/+ compared to cPLA2alpha-/- ischemic cortex. Neuronal swelling in ischemic regions was significantly greater in the cPLA2alpha+/+ than in cPLA2alpha-/- brains (+/+:2.2+/-0.3 fold vs. -/-:1.7+/-0.4 fold increase; P<0.01). The increase in reactive oxygen species following 2 hours of ischemia was also significantly greater in the cPLA2alpha+/+ ischemic core than in cPLA2alpha-/- (+/+:7.12+/-1.2 fold vs. -/-:3.1+/-1.4 fold; P<0.01). After 6 hours of reperfusion ischemic cortex of cPLA2alpha+/+, but not cPLA2alpha-/-, had disruption of neuron morphology and decreased PGE2 content. Phosphorylation of the MAPKs-p38, ERK 1/2, and MEK 1/2-was significantly greater in cPLA2a+/+ than in cPLA2alpha-/- ischemic cortex 6 hours after reperfusion.
These results indicate that cPLA2alpha modulates the earliest molecular and injury responses after cerebral ischemia and have implications for the potential clinical use of cPLA2alpha inhibitors.
Journal of Neuroinflammation 01/2010; 7:42. · 3.83 Impact Factor
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ABSTRACT: Abstract
Background
The enzyme cytosolic phospholipase A<sub>2 </sub>alpha (cPLA<sub>2</sub>α) has been implicated in the progression of cerebral injury following ischemia and reperfusion. Previous studies in rodents suggest that cPLA<sub>2</sub>α enhances delayed injury extension and disruption of the blood brain barrier many hours after reperfusion. In this study we investigated the role of cPLA<sub>2</sub>α in early ischemic cerebral injury.
Methods
Middle cerebral artery occlusion (MCAO) was performed on cPLA<sub>2</sub>α<sup>+/+ </sup>and cPLA<sub>2</sub>α<sup>-/- </sup>mice for 2 hours followed by 0, 2, or 6 hours of reperfusion. The levels of cPLA<sub>2</sub>α, cyclooxygenase-2, neuronal morphology and reactive oxygen species in the ischemic and contralateral hemispheres were evaluated by light and fluorescent microscopy. PGE<sub>2 </sub>content was compared between genotypes and hemispheres after MCAO and MCAO and 6 hours reperfusion. Regional cerebral blood flow was measured during MCAO and phosphorylation of relevant MAPKs in brain protein homogenates was measured by Western analysis after 6 hours of reperfusion.
Results
Neuronal cPLA<sub>2</sub>α protein increased by 2-fold immediately after MCAO and returned to pre-MCAO levels after 2 hours reperfusion. Neuronal cyclooxygenase-2 induction and PGE<sub>2 </sub>concentration were greater in cPLA<sub>2</sub>α<sup>+/+ </sup>compared to cPLA<sub>2</sub>α<sup>-/- </sup>ischemic cortex. Neuronal swelling in ischemic regions was significantly greater in the cPLA<sub>2</sub>α<sup>+/+ </sup>than in cPLA<sub>2</sub>α<sup>-/- </sup>brains (+/+: 2.2 ± 0.3 fold vs. -/-: 1.7 ± 0.4 fold increase; P < 0.01). The increase in reactive oxygen species following 2 hours of ischemia was also significantly greater in the cPLA<sub>2</sub>α<sup>+/+ </sup>ischemic core than in cPLA<sub>2</sub>α<sup>-/- </sup>(+/+: 7.12 ± 1.2 fold vs. -/-: 3.1 ± 1.4 fold; P < 0.01). After 6 hours of reperfusion ischemic cortex of cPLA<sub>2</sub>α<sup>+/+</sup>, but not cPLA<sub>2</sub>α<sup>-/-</sup>, had disruption of neuron morphology and decreased PGE<sub>2 </sub>content. Phosphorylation of the MAPKs-p38, ERK 1/2, and MEK 1/2-was significantly greater in cPLA<sub>2</sub>a<sup>+/+ </sup>than in cPLA<sub>2</sub>α<sup>-/- </sup>ischemic cortex 6 hours after reperfusion.
Conclusions
These results indicate that cPLA<sub>2</sub>α modulates the earliest molecular and injury responses after cerebral ischemia and have implications for the potential clinical use of cPLA<sub>2</sub>α inhibitors.
Journal of Neuroinflammation. 01/2010;
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ABSTRACT: Telemedicine has been studied in the intensive care unit for several decades, but many questions remain unanswered regarding the costs and the benefits of its application. Telemedicine ICU (Tele-ICU) is an electronic means to link physical ICUs to another location which assists in medical decision making. Given the shortage of intensive care physicians in the US, Tele-ICU systems could be an efficient mechanism for physicians to manage a larger number of critical care patients. This chapter will examine the current state of telemedicine in an age of rapidly expanding medical information technology and increasing demand for intensive care services. While we believe that the future of Tele-ICU is promising, there are multiple issues that must be addressed to increase the benefit of Tele-ICU. Tele-ICU is expensive to deploy and use, it may add burdens to existing intensivists, and it requires organizational and culture changes that can be difficult to accomplish.
Baillière' s Best Practice and Research in Clinical Anaesthesiology 04/2009; 23(1):115-26.
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ABSTRACT: The arachidonic acid-generating enzyme cytosolic phospholipase A(2) alpha (cPLA(2)alpha) has been implicated in the progression of excitotoxic neuronal injury. However, the mechanisms of cPLA(2)alpha toxicity have yet to be determined. Here, we used a model system exposing mouse hippocampal slices to NMDA as an excitotoxic injury, in combination with simultaneous patch-clamp recording and confocal Ca(2+) imaging of CA1 pyramidal neurons. NMDA treatment caused significantly greater injury in wild-type (WT) than in cPLA(2)alpha null CA1 neurons. Bath application of NMDA evoked a slow inward current in voltage-clamped neurons (composed of both NMDA receptor-mediated and other conductances) that was smaller in cPLA(2)alpha null than in WT slices. This was not due to down-regulation of NMDA receptor function because NMDA receptor-mediated currents were equivalent in each genotype following brief photolysis of caged glutamate. Current-clamp recordings were made during and following NMDA exposure by eliciting a single action potential with a brief current injection. After NMDA exposure, WT CA1 neurons developed a spike-evoked plateau potential and an increased spike-evoked dendritic Ca(2+) transient. These effects were absent in CA1 neurons from cPLA(2)alpha null mice and WT neurons treated with a cPLA(2)alpha inhibitor. The Ca-sensitive K-channel toxins, apamin and paxilline, caused spike broadening and Ca(2+) enhancement in WT and cPLA(2)alpha null slices. NMDA application in WT and arachidonate applied to cPLA(2)alpha null cells occluded the effects of apamin/paxilline. These results indicate that cPLA(2)alpha activity is required for development of aberrant electrophysiologic events triggered by NMDA receptor activation, in part through attenuation of K-channel function.
Proceedings of the National Academy of Sciences 05/2007; 104(14):6078-83. · 9.68 Impact Factor
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ABSTRACT: The arachidonic acid-specific cytosolic phospholipase A(2) alpha (cPLA(2)alpha) has been implicated in the generation of neurological injuries. cPLA(2)alpha-dependent neurological injury has been postulated to be mediated through inflammatory and eicosanoid pathways. We determined if cPLA(2)alpha amplifies the injury of a non-inflammatory, excitotoxic stimulus by modifying a well-described toxicity assay to measure the toxicity of N-methyl-d-aspartate (NMDA) in the CA1 region of organotypic, mouse hippocampal cultures. Hippocampal cultures from wild-type and cPLA(2)alpha knockout mice were exposed to 5, 7.5 or 10 microm NMDA for 1 h. Toxicity was measured 23 h later. Cultures derived from cPLA(2)alpha(-/-) mice and cultures treated with the selective inhibitor AACOCF(3) were significantly protected from NMDA toxicity, as compared with wild-type cultures. To determine if cPLA(2)alpha-dependent toxicity is cyclooxygenase (COX)-2 dependent, COX-2 and PGE(2) levels were measured 7 and 25 h after NMDA treatment. NMDA treatment failed to induce COX-2 protein or increase PGE(2) in the culture media in either genotype at either time. In contrast, phorbol 12-myristate 13-acetate and ionophore treatment caused robust induction of COX-2 and PGE(2) in both genotypes. We conclude that cPLA(2)alpha may have a hitherto unrecognized direct effect on excitatory neurotoxicity, suggesting that cPLA(2)alpha inhibition is a therapeutic candidate for treatment of the early, excitotoxic injury observed in stroke.
European Journal of Neuroscience 01/2007; 24(12):3381-6. · 3.63 Impact Factor
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ABSTRACT: To perform an analysis of the Medicare claims database in patients undergoing lung resection to determine whether there is an association between postoperative epidural analgesia and mortality.
Retrospective cohort (database) design.
University hospital.
We examined a cohort of 3501 patients obtained from a 5% nationally random sample of 1997 to 2001 Medicare beneficiaries who underwent nonemergency segmental excision of the lung (International Classification of Diseases, 9th Revision, Clinical Modification codes 32.3 and 32.4). Patient data were divided into two groups depending on the presence or absence of billing for postoperative epidural analgesia (Current Procedural Terminology code 01996). The primary outcomes assessed were death at 7 and 30 days after the procedure. The rates of major morbidity (acute myocardial infarction, angina, cardiac dysrhythmias, heart failure, pneumonia, pulmonary edema, respiratory failure, deep venous thrombosis, pulmonary embolism, sepsis, acute renal failure, somnolence, acute cerebrovascular event, transient organic syndrome, and paralytic ileus) were also compared. Multivariate regression analysis incorporating race, gender, age, comorbidities, hospital size, hospital teaching status, and hospital technology status was performed to determine whether the presence of postoperative epidural analgesia had an independent effect on mortality or major morbidity.
Multivariate regression analysis showed that the presence of epidural analgesia was associated with a significantly lower odds of death at 7 days (odds ratio, 0.39; 95% confidence interval, 0.19-0.80; P = 0.001) and 30 days (odds ratio, 0.53; 95% confidence interval, 0.35-0.78; P = 0.002) after surgery. There was no difference between the groups with regard to overall major morbidity.
Postoperative epidural analgesia may contribute to lower odds of death after segmental excision of the lung, although the mechanism of such a benefit is not clear from our analysis.
Journal of Clinical Anesthesia 12/2006; 18(7):515-20. · 1.21 Impact Factor
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ABSTRACT: Osmotherapy is the cornerstone of medical management for cerebral edema associated with large ischemic strokes. We determined the effect of duration of graded increases in serum osmolality with mannitol and hypertonic saline (HS) on blood-brain barrier (BBB) disruption and regional cerebral edema in a well-characterized rat model of large ischemic stroke. Halothane-anesthetized adult male Wistar rats were subjected to transient (2-h) middle cerebral artery occlusion (MCAO) by the intraluminal occlusion technique. Beginning at 6 h after MCAO, rats were treated with either no intravenous fluids or a continuous intravenous infusion (0.3 mL/h) of 0.9% saline, 20% mannitol, 3% HS, or 7.5% HS for 24, 48, 72, and 96 h. In the first series of experiments, BBB permeability was quantified by the Evans blue (EB) extravasation method. In the second series of experiments, water content was assessed by comparing wet-to-dry weight ratios in six predetermined brain regions. Blood-brain barrier disruption was maximal in rats treated with 0.9% saline for 48 h, but did not correlate with increases in serum osmolality or treatment duration with osmotic agents. Treatment with 7.5% HS attenuated water content in the periinfarct regions and all subregions of the contralateral nonischemic hemisphere to a greater extent than mannitol did with no adverse effect on survival rates. These data show that (1) BBB integrity is not affected by the duration and degree of serum osmolality with osmotic agents, and (2) attenuation of increases in brain water content with HS to target levels >350 mOsm/L may have therapeutic implications in the treatment of cerebral edema associated with ischemic stroke.
Journal of Cerebral Blood Flow & Metabolism 07/2006; 26(7):951-8. · 5.01 Impact Factor
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ABSTRACT: F2-isoprostanes are produced in vivo by nonenzymatic peroxidation of arachidonic acid esterified in phospholipids. Increased urinary and plasma F2-isoprostane levels are associated with a number of human diseases. These metabolites are regarded as excellent markers of oxidant stress in vivo. Isoprostanes are initially generated in situ, i.e. when the arachidonate precursor is esterified in phospholipids, and they are subsequently released in free form. Although the mechanism(s) responsible for the release of free isoprostanes after in situ generation in membrane phospholipids is, for the most part, unknown, this process is likely mediated by phospholipase A2 activity(ies). Here we reported that human plasma contains an enzymatic activity that catalyzes this reaction. The activity associates with high density and low density lipoprotein and comigrates with platelet-activating factor (PAF) acetylhydrolase on KBr density gradients. Plasma samples from subjects deficient in PAF acetylhydrolase do not release F2-isoprostanes from esterified precursors. The intracellular PAF acetylhydrolase II, which shares homology to the plasma enzyme, also catalyzes this reaction. We found that both the intracellular and plasma PAF acetylhydrolases have high affinity for esterified F2-isoprostanes. However, the rate of esterified F2-isoprostane hydrolysis is much slower compared with the rate of hydrolysis of other substrates utilized by these enzymes. Studies using PAF acetylhydrolase transgenic mice indicated that these animals have a higher capacity to release F2-isoprostanes compared with nontransgenic littermates. Our results suggested that PAF acetylhydrolases play key roles in the hydrolysis of F2-isoprostanes esterified on phospholipids in vivo.
Journal of Biological Chemistry 03/2006; 281(8):4616-23. · 4.77 Impact Factor
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ABSTRACT: F2-isoprostanes are produced in vivo by nonenzymatic peroxidation of arachidonic acid esterified in phospholipids. Increased urinary and plasma F2-isoprostane levels are associated with a number of human diseases. These metabolites are regarded as excellent markers of
oxidant stress in vivo. Isoprostanes are initially generated in situ, i.e. when the arachidonate precursor is esterified in phospholipids, and they are subsequently released in free form. Although
the mechanism(s) responsible for the release of free isoprostanes after in situ generation in membrane phospholipids is, for the most part, unknown, this process is likely mediated by phospholipase A2 activity(ies). Here we reported that human plasma contains an enzymatic activity that catalyzes this reaction. The activity
associates with high density and low density lipoprotein and comigrates with platelet-activating factor (PAF) acetylhydrolase
on KBr density gradients. Plasma samples from subjects deficient in PAF acetylhydrolase do not release F2-isoprostanes from esterified precursors. The intracellular PAF acetylhydrolase II, which shares homology to the plasma enzyme,
also catalyzes this reaction. We found that both the intracellular and plasma PAF acetylhydrolases have high affinity for
esterified F2-isoprostanes. However, the rate of esterified F2-isoprostane hydrolysis is much slower compared with the rate of hydrolysis of other substrates utilized by these enzymes.
Studies using PAF acetylhydrolase transgenic mice indicated that these animals have a higher capacity to release F2-isoprostanes compared with nontransgenic littermates. Our results suggested that PAF acetylhydrolases play key roles in the
hydrolysis of F2-isoprostanes esterified on phospholipids in vivo.
Journal of Biological Chemistry 02/2006; 281(8):4616-4623. · 4.77 Impact Factor
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ABSTRACT: Differential neurological outcomes due to prostaglandin E2 activating G-protein-coupled prostaglandin E (EP) receptors have been observed. Here, we investigated the action of the EP4/EP3 agonist 1-hydroxyPGE1 (1-OHPGE1) in modulating transient ischemic brain damage. C57BL/6 mice were pretreated 50 min before transient occlusion of the middle cerebral artery with an intraventricular injection of 1-OHPGE1 (0.1, 0.2, 2.0 nmol/0.2 microL). Brain damage 4 days after reperfusion, as estimated by infarct volume, was significantly reduced by more than 19% with 1-OHPGE1 in the two higher-dose groups (P < 0.05). To further address whether protection also was extended to neurons, primary mouse cultured neuronal cells were exposed to N-methyl-D-aspartate. Co-treatment with 1-OHPGE1 resulted in significant neuroprotection (P < 0.05). To better understand potential mechanisms of action and to test whether changes in cyclic adenosine monophosphate (cAMP) levels and downstream signaling would be neuroprotective, we measured cAMP levels in primary neuronal cells. Brief exposure to 1-OHPGE1 increased cAMP levels more than twofold and increased the phosphorylation of extracellular-regulated kinases at positions Thr-202/Tyr-204. In a separate cohort of animals, 1-OHPGE1 at all doses tested produced no significant effect on the physiological parameters of core body temperature, mean arterial pressure and relative cerebral blood flow observed following drug treatment. Together, these results suggest that modulation of PGE2 receptors that increase cAMP levels and activate extracellular-regulated kinases 1/2 caused by treatment with 1-OHPGE1 can be protective against neuronal injury induced by focal ischemia.
European Journal of Neuroscience 01/2006; 23(1):35-42. · 3.63 Impact Factor
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ABSTRACT: The products of arachidonic acid metabolism are key mediators of inflammatory responses in the central nervous system, and yet we do not know the mechanisms of their regulation. The phospholipase A(2) enzymes are sources of cellular arachidonic acid, and the enzymes cyclooxygenase-2 (COX-2) and microsomal PGE synthase-1 (mPGES-1) are essential for the synthesis of inflammatory PGE(2) in the brain. These studies seek to determine the function of cytosolic phospholipase A(2)alpha (cPLA(2)alpha) in inflammatory PGE(2) production in the brain. We wondered whether cPLA(2)alpha functions in inflammation to produce arachidonic acid or to modulate levels of COX-2 or mPGES-1. We investigated these questions in the brains of wild-type mice and mice deficient in cPLA(2)alpha (cPLA(2)alpha(-/-)) after systemic administration of LPS. cPLA(2)alpha(-/-) mice had significantly less brain COX-2 mRNA and protein expression in response to LPS than wild-type mice. The reduction in COX-2 was most apparent in the cells of the cerebral blood vessels and the leptomeninges. The brain PGE(2) concentration of untreated cPLA(2)alpha(-/-) mice was equal to their wild-type littermates. After LPS treatment, however, the brain concentration of PGE(2) was significantly less in cPLA(2)alpha(-/-) than in cPLA(2)alpha(+/+) mice (24.4 +/- 3.8 vs. 49.3 +/- 11.6 ng/g). In contrast to COX-2, mPGES-1 RNA levels increased equally in both mouse genotypes, and mPGES-1 protein was unaltered 6 h after LPS. We conclude that cPLA(2)alpha regulates COX-2 levels and modulates inflammatory PGE(2) levels. These results indicate that cPLA(2)alpha inhibition is a novel anti-inflammatory strategy that modulates, but does not completely prevent, eicosanoid responses.
AJP Regulatory Integrative and Comparative Physiology 07/2005; 288(6):R1774-82. · 3.34 Impact Factor
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ABSTRACT: Heme oxygenase-2 (HO-2) has been suggested to be a cytoprotective enzyme in a variety of in vivo experimental models. HO-2, the constitutive isozyme, is enriched in neurons and, under normal conditions, accounts for nearly all of brain HO activity. HO-2 deletion (HO-2-/-) leads to increased neurotoxicity in cultured brain cells and increased damage following transient cerebral ischemia in mice. Moreover, pharmacologic inhibition of HO activity significantly augments focal ischemic damage in wildtype (WT) mice, but does not further exacerbate it in HO-2-/- mice. The HO system shares some similarities with nitric oxide synthase (NOS), notably their syntheses of carbon monoxide (CO) and nitric oxide (NO), respectively, which are diffusible gases with numerous biological actions, including neurotransmission and vasodilation. While deletion of HO-2 results in greater stroke damage, the pharmacologic inhibition of neuronal nitric oxide synthase (nNOS), or its gene deletion, confers neuroprotection in animal models of transient cerebral ischemia. To investigate the interactions, the outcome of focal cerebral ischemia-reperfusion in double knockout (HO-2-/- X nNOS-/-) mice lacking both genes was compared to control WT mice. Wildtype and double knockout male mice underwent intraluminal middle cerebral occlusion for 2 hours, followed by reperfusion for 22 hours. Outcomes in neurologic deficits and infarct size were determined. No difference was observed between WT and double knockout mice in the volume of infarction, neurologic signs, decrease in relative cerebral blood flow during ischemia, or core body temperature. The results suggest that the deleterious action of nNOS would counteract the role of HO-2 in neuroprotection.
Current Neurovascular Research 02/2005; 2(1):23-7. · 2.72 Impact Factor
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ABSTRACT: Oxidant stress and phospholipase A2 (PLA2) activation have been implicated in numerous proinflammatory responses of the mesangial cell (MC). We investigated the cross-talk between group IValpha cytosolic PLA2 (cPLA2alpha) and secretory PLA2s (sPLA2s) during H2O2-induced arachidonic acid (AA) release using two types of murine MC: (i). MC+/+, which lack group IIa and V PLA2s, and (ii). MC-/-, which lack groups IIa, V, and IValpha PLA2s. H2O2-induced AA release was greater in MC+/+ compared with MC-/-. It has been argued that cPLA2alpha plays a regulatory role enhancing the activity of sPLA2s, which act on phospholipids to release fatty acid. Group IIa, V, or IValpha PLA2s were expressed in MC-/- or MC+/+ using recombinant adenovirus vectors. Expression of cPLA2alpha in H2O2-treated MC-/- increased AA release to a level approaching that of H2O2-treated MC+/+. Expression of either group IIa PLA2 or V PLA2 enhanced AA release in MC+/+ but had no effect on AA release in MC-/-. When sPLA2 and cPLA2alpha are both present, the effect of H2O2 is manifested by preferential release of AA compared with oleic acid. Inhibition of the ERK and protein kinase C signaling pathways with the MEK-1 inhibitor, U0126, and protein kinase C inhibitor, GF 1092030x, respectively, and chelating intracellular free calcium with 1,2-bis(2-aminophenoyl)ethane-N,N,N',N'-tetraacetic acid-AM, which also reduced ERK1/2 activation, significantly reduced H2O2-induced AA release in MC+/+ expressing either group IIa or V PLA2s. By contrast, H2O2-induced AA release was not enhanced when ERK1/2 was activated by infection of MC+/+ with constitutively active MEK1-DD. We conclude that the effect of group IIa and V PLA2s on H2O2-induced AA release is dependent upon the presence of cPLA2alpha and the activation of PKC and ERK1/2. Group IIa and V PLA2s are regulatory and cPLA2alpha is responsible for AA release.
Journal of Biological Chemistry 07/2003; 278(26):24153-63. · 4.77 Impact Factor
