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1

Naloxone Blockade of Myocardial Ischemic Preconditioning is Stereoselective  

Microsoft Academic Search

This study tested the hypothesis that endogenous opioids are involved in the infarct limitation of myocardial ischemic preconditioning (IP). Blockade of IP-induced infarct limitation by (?)naloxone hydrochloride (?NAL) or its receptor-inactive stereoisomer (+)naloxone (+NAL) was evaluated. Fifty-two pentobarbitone-anesthetized, open-chest rabbits underwent 30 min coronary artery occlusion and 180 min reperfusion. Treatment groups were: control (n=9), IP (n=8), ?NAL (n=9) and

Grace L. Chien; Donna M. Van Winkle

1996-01-01

2

Ischemic preconditioning. Experimental facts and clinical perspective.  

PubMed

Brief periods of non-lethal ischemia and reperfusion render the myocardium more resistant to subsequent ischemia. This adaption occurs in a biphasic pattern: the first being active immediately and lasting for 2-3 hrs (early preconditioning), the second starting at 24 hrs until 72 hrs after the initial ischemia (delayed preconditioning) and requiring genomic activation with de novo protein synthesis. Early preconditioning is more potent than delayed preconditioning in reducing infarct size; delayed preconditioning also attenuates myocardial stunning. Early preconditioning depends on the ischemia-induced release of adenosine and opioids and, to a lesser degree, also bradykinin and prostaglandins. These molecules activate G-protein coupled receptors, initiate the activation of KATP channels and generation of oxygen radicals, and stimulate a series of protein kinases with essential roles for protein kinase C, tyrosine kinases and members of the MAP kinase family. Delayed preconditioning is triggered by a similar sequence of events, but in addition essentially depends on eNOS-derived NO. Both early and pharmacological preconditioning can be pharmacologically mimicked by exogenous adenosine, opioids, NO and activators of protein kinase C. Newly synthetized proteins associated with delayed preconditioning comprise iNOS, COX-2, manganese superoxide dismutase and possibly heat shock proteins. The final mechanism of protection by preconditioning is yet unknown; energy metabolism, KATP channels, the sodium-proton exchanger, stabilisation of the cytoskeleton and volume regulation will be discussed. For ethical reasons, evidence for ischemic preconditioning in humans is hard to provide. Clinical findings that parallel experimental ischemic preconditioning are reduced ST-segment elevation and pain during repetitive PTCA or exercise tests, a better prognosis of patients in whom myocardial infarction was preceded by angina, and reduced serum markers of myocardial necrosis after preconditioning protocols during cardiac surgery with cardiac arrest. The most promising approach to apply principles of ischemic preconditioning therapeutically appears to be the pharmacological recruitment of delayed protection, as recently demonstrated with intravenous nitroglycerine in patients undergoing PTCA 24 hrs later. PMID:12473980

Post, H; Heusch, G

2002-12-01

3

Resveratrol and ischemic preconditioning in the brain.  

PubMed

Cardiovascular pathologies in the French are not prevalent despite high dietary saturated fat consumption. This is commonly referred to as the "French Paradox" attributing its anti-lipidemic effects to moderate consumption of red wine. Resveratrol, a phytoalexin found in red wine, is currently the focus of intense research both in the cardiovascular system and the brain. Current research suggests resveratrol may enhance prognosis of neurological disorders such as, Parkinson's, Huntington's, Alzheimer's diseases and stroke. The beneficial effects of resveratrol include: antioxidation, free radical scavenger, and modulation of neuronal energy homeostasis and glutamatergic receptors/ion channels. Resveratrol directly increases sirtuin 1 (SIRT1) activity, a NAD(+) (oxidized form of nicotinamide adenine dinucleotide)-dependent histone deacetylase related to increased lifespan in various species similar to calorie restriction. We recently demonstrated that brief resveratrol pretreatment conferred neuroprotection against cerebral ischemia via SIRT1 activation. This neuroprotective effect produced by resveratrol was similar to ischemic preconditioning-induced neuroprotection, which protects against lethal ischemic insults in the brain and other organ systems. Inhibition of SIRT1 abolished ischemic preconditioning-induced neuroprotection in CA1 region of the hippocampus. Since resveratrol and ischemic preconditioning-induced neuroprotection require activation of SIRT1, this common signaling pathway may provide targeted therapeutic treatment modalities as it relates to stroke and other brain pathologies. In this review, we will examine common signaling pathways, cellular targets of resveratrol, and ischemic preconditioning-induced neuroprotection as it relates to the brain. PMID:18537630

Raval, Ami P; Lin, Hung Wen; Dave, Kunjan R; Defazio, R Anthony; Della Morte, David; Kim, Eun Joo; Perez-Pinzon, Miguel A

2008-01-01

4

An electrocardiographic sign of ischemic preconditioning.  

PubMed

Ischemic preconditioning is a form of intrinsic cardioprotection where an episode of sublethal ischemia protects against subsequent episodes of ischemia. Identifying a clinical biomarker of preconditioning could have important clinical implications, and prior work has focused on the electrocardiographic ST segment. However, the electrophysiology biomarker of preconditioning is increased action potential duration (APD) shortening with subsequent ischemic episodes, and APD shortening should primarily alter the T wave, not the ST segment. We translated findings from simulations to canine to patient models of preconditioning to test the hypothesis that the combination of increased [delta (?)] T wave amplitude with decreased ST segment elevation characterizes preconditioning. In simulations, decreased APD caused increased T wave amplitude with minimal ST segment elevation. In contrast, decreased action potential amplitude increased ST segment elevation significantly. In a canine model of preconditioning (9 mongrel dogs undergoing 4 ischemia-reperfusion episodes), ST segment amplitude increased more than T wave amplitude during the first ischemic episode [?T/?ST slope = 0.81, 95% confidence interval (CI) 0.46-1.15]; however, during subsequent ischemic episodes the T wave increased significantly more than the ST segment (?T/?ST slope = 2.43, CI 2.07-2.80) (P < 0.001 for interaction of occlusions 2 vs. 1). A similar result was observed in patients (9 patients undergoing 2 consecutive prolonged occlusions during elective percutaneous coronary intervention), with an increase in slope of ?T/?ST of 0.13 (CI -0.15 to 0.42) in the first occlusion to 1.02 (CI 0.31-1.73) in the second occlusion (P = 0.02). This integrated analysis of the T wave and ST segment goes beyond the standard approach to only analyze ST elevation, and detects cellular electrophysiology changes of preconditioning. PMID:24778173

Meijs, Loek P B; Galeotti, Loriano; Pueyo, Esther P; Romero, Daniel; Jennings, Robert B; Ringborn, Michael; Warren, Stafford G; Wagner, Galen S; Strauss, David G

2014-07-01

5

Effects of ischemic preconditioning on cyclinD1 expression during early ischemic reperfusion in rats  

PubMed Central

AIM: To observe the effect of ischemic preconditioning on cyclinD1 expression in rat liver cells during early ischemic reperfusion. METHODS: Fifty-four SD rats were randomly divided into ischemic preconditioning group (IP), ischemia/reperfusion group (IR) and sham operation group (SO). The IP and IR groups were further divided into four sub-groups (n = 6). Sham operation group (SO) served as the control group (n = 6). A model of partial liver ischemia/reperfusion was used, in which rats were subjected to liver ischemia for 60 min prior to reperfusion. The animals in the IP group underwent ischemic preconditioning twice for 5 min each time prior to the ischemia/reperfusion challenge. After 0, 1, 2, and 4 h of reperfusion, serum and liver tissue in each group were collected to detect the level of serum ALT, liver histopathology and expression of cyclinD1 mRNA and protein. Flow cytometry was used to detect cell cycle as the quantity indicator of cell regeneration. RESULTS: Compared with IR group, IP group showed a significantly lower ALT level in 1 h to 4 h sub-groups (P < 0.05). Proliferation index(PI) indicated by the S-phase and G2/M-phase ratio [(S+G2/M)/(G0/G1+S+G2/M)] was significantly increased in IP group at 0 and 1 h (26.44± 7.60% vs 18.56 ± 6.40%,41.87 ± 7.27% vs 20.25 ± 6.70%, P < 0.05). Meanwhile, cyclinD1 protein expression could be detected in IP group. But in IR group, cyclinD1 protein expression occurred 2 h after reperfusion. The expression of cyclinD1 mRNA increased significantly in IP group at 0 and 1 h (0.568 ± 0.112 vs 0.274 ± 0.069, 0.762 ± 0.164 vs 0.348 ± 0.093, P < 0.05). CONCLUSION: Ischemic preconditioning can protect liver cells against ischemia/reperfusion injury, which may be related to cell proliferation and expression of cyclinD1 during early ischemic reperfusion. PMID:16718823

Cai, Fang-Gang; Xiao, Jian-Sheng; Ye, Qi-Fa

2006-01-01

6

Clinical Applications of Remote Ischemic Preconditioning  

PubMed Central

Ischemia-reperfusion injury is a composite of damage accumulated during reduced perfusion of an organ or tissue and the additional insult sustained during reperfusion. Such injury occurs in a wide variety of clinically important syndromes, such as ischemic heart disease and stroke, which are responsible for a high degree of morbidity and mortality worldwide. Basic research has identified a number of interventions that stimulate innate resistance of tissues to ischemia-reperfusion injury. Here, we summarise the experimental and clinical trial data underpinning one of these “conditioning” strategies, the phenomenon of remote ischemic preconditioning. PMID:22400123

Veighey, Kristin; MacAllister, Raymond J.

2012-01-01

7

Ischemic Preconditioning Prevents Free Radical Production and Mitochondrial Depolarization in Small-for-Size Rat Liver Grafts  

Microsoft Academic Search

Background. Ischemic preconditioning (IP) renders tissues more tolerant to subsequent longer episodes of ischemia. This study tested whether IP attenuates injury of small-for-size liver grafts by preventing free radical production and mitochondrial dysfunction. Methods. IP was induced by clamping the portal vein and hepatic artery for 9 min. Livers were harvested 5 min after releasing the clamp. Mitochondrial polarization and

Hasibur Rehman; Henry D. Connor; Venkat K. Ramshesh; Tom P. Theruvath; Ronald P. Mason; Gary L. Wright; John J. Lemasters; Zhi Zhong

2008-01-01

8

Prevention of the ischemia-induced decrease in mitochondrial Tom20 content by ischemic preconditioning.  

PubMed

Preserved mitochondrial function (respiration, calcium handling) and integrity (cytochrome c release) is central for cell survival following ischemia/reperfusion. Mitochondrial function also requires import of proteins from the cytosol via the translocase of the outer and inner membrane (TOM and TIM complexes). Since mitochondrial function following ischemia/reperfusion is better preserved by ischemic preconditioning (IP), we now investigated whether expression of parts of the import machinery is affected by ischemia/reperfusion without or with IP in vivo. We analyzed the mitochondrial content of the presequence receptor Tom20, the pore forming unit Tom40 and Tim23. Goettinger minipigs were subjected to 90 min of low-flow ischemia without or with preconditioning by 10 min ischemia and 15 min reperfusion. Mitochondria were isolated from the ischemic or preconditioned anterior wall of the left ventricle and from the control posterior wall. Infarct size was significantly reduced by IP (20.1 +/- 1.6% of area at risk (non-preconditioned) vs. 6.5 +/- 2.5% of area at risk (IP)). Using Western blot analysis, the ratio of Tom20 (normalized to Ponceau S) between mitochondria isolated from the anterior ischemic and posterior control wall was reduced (0.72 +/- 0.11, a.u., n = 8), whereas the mitochondrial Tom20 content was preserved by IP (1.17 +/- 0.16 a.u., n = 7, P < 0.05). The mitochondrial Tom40, Tim23 and adenine nucleotide transporter (ANT) contents were not significantly different between non-preconditioned and preconditioned myocardium. The preservation of the mitochondrial Tom20 protein level may contribute to the improved mitochondrial function after IP. PMID:16828795

Boengler, Kerstin; Gres, Petra; Cabestrero, Alberto; Ruiz-Meana, Marisol; Garcia-Dorado, David; Heusch, Gerd; Schulz, Rainer

2006-09-01

9

GABA synapses mediate neuroprotection after ischemic and ?PKC preconditioning in rat hippocampal slice cultures  

Microsoft Academic Search

Delayed neuroprotection against ischemic challenges is conferred by both ischemic preconditioning (IPC) and preconditioning by activation of the ?-isoform of protein kinase C (?PKC-PC). In vivo, ischemic preconditioning enhances GABA release and ameliorates glutamate release during lethal cerebral ischemia. We tested the hypothesis that IPC and ?PKC-PC confer neuroprotection by GABA synapses in rat organotypic hippocampal slices. Ischemic preconditioning or

R Anthony DeFazio; Ami P Raval; Hung W Lin; Kunjan R Dave; David Della-Morte; Miguel A Perez-Pinzon

2009-01-01

10

Essential Role of Lipid Raft in Ischemic Preconditioning  

Microsoft Academic Search

Lipid rafts represent a subcompartment of the plasma membrane that coordinate and regulate varieties of signaling processes while caveolins are the integral membrane protein of the lipid raft. To study the role of lipid raft in ischemic preconditioning (PC) of the heart, rat hearts were perfused by working mode and then preconditioned in absence or presence of a lipid raft

Manika Das; Mihaela Gherghiceanu; Istvan Lekli; Subhendu Mukherjee; Lawrence M. Popescu; Dipak K. Das

2008-01-01

11

Effects of Ischemic Preconditioning of Different Intraoperative Ischemic Times of Vascularized Bone Graft Rabbit Models  

PubMed Central

Background Ischemic preconditioning has been shown to improve the outcomes of hypoxic tolerance of the heart, brain, lung, liver, jejunum, skin, and muscle tissues. However, to date, no report of ischemic preconditioning on vascularized bone grafts has been published. Methods Sixteen rabbits were divided into four groups with ischemic times of 2, 6, 14, and 18 hours. Half of the rabbits in each group underwent ischemic preconditioning. The osteomyocutaneous flaps consisted of the tibia bone, from which the overlying muscle and skin were raised. The technique of ischemic preconditioning involved applying a vascular clamp to the pedicle for 3 cycles of 10 minutes each. The rabbits then underwent serial plain radiography and computed tomography imaging on the first, second, fourth, and sixth postoperative weeks. Following this, all of the rabbits were sacrificed and histological examinations were performed. Results The results showed that for clinical analysis of the skin flaps and bone grafts, the preconditioned groups showed better survivability. In the plain radiographs, except for two non-preconditioned rabbits with intraoperative ischemic times of 6 hours, all began to show early callus formation at the fourth week. The computed tomography findings showed more callus formation in the preconditioned groups for all of the ischemic times except for the 18-hour group. The histological findings correlated with the radiological findings. There was no statistical significance in the difference between the two groups. Conclusions In conclusion, ischemic preconditioning improved the survivability of skin flaps and increased callus formation during the healing process of vascularized bone grafts. PMID:24286040

Wan Ahmad Kamal, Wan Syazli Rodzaia; Noor, Norizal Mohd; Abdullah, Shafie

2013-01-01

12

The protective roles of autophagy in ischemic preconditioning  

PubMed Central

Autophagy, a process for the degradation of protein aggregates and dysfunctional organelles, is required for cellular homeostasis and cell survival in response to stress and is implicated in endogenous protection. Ischemic preconditioning is a brief and nonlethal episode of ischemia, confers protection against subsequent ischemia-reperfusion through the up-regulation of endogenous protective mechanisms. Emerging evidence shows that autophagy is associated with the protective effect of ischemic preconditioning. This review summarizes recent progress in research on the functions and regulations of the autophagy pathway in preconditioning-induced protection and cellular survival. PMID:23603984

Yan, Wen-jun; Dong, Hai-long; Xiong, Li-ze

2013-01-01

13

Autophagy Induced by Ischemic Preconditioning is Essential for Cardioprotection  

Microsoft Academic Search

Based on growing evidence linking autophagy to preconditioning, we tested the hypothesis that autophagy is necessary for cardioprotection\\u000a conferred by ischemic preconditioning (IPC). We induced IPC with three cycles of 5 min regional ischemia alternating with\\u000a 5 min reperfusion and assessed the induction of autophagy in mCherry-LC3 transgenic mice by imaging of fluorescent autophagosomes\\u000a in cryosections. We found a rapid and significant

Chengqun Huang; Smadar Yitzhaki; Cynthia N. Perry; Wayne Liu; Zoltan Giricz; Robert M. Mentzer Jr; Roberta A. Gottlieb

2010-01-01

14

Tandem action of exercise training and food restriction completely preserves ischemic preconditioning in the aging heart.  

PubMed

Ischemic preconditioning (IP) has been proposed as an endogenous form of protection against ischemia reperfusion injury. IP, however, does not prevent post-ischemic dysfunction in the aging heart but may be partially corrected by exercise training and food restriction. We investigated the role of exercise training combined with food restriction on restoring IP in the aging heart. Effects of IP against ischemia-reperfusion injury in isolated hearts from adult (A, 6 months old), sedentary 'ad libitum' fed (SL), trained ad libitum fed (TL), sedentary food-restricted (SR), trained- and food-restricted senescent rats (TR) (24 months old) were investigated. Norepinephrine release in coronary effluent was determined by high performance liquid cromatography. IP significantly improved final recovery of percent developed pressure in hearts from A (p<0.01) but not in those from SL (p=NS) vs unconditioned controls. Developed pressure recovery was partial in hearts from TL and SR (64.3 and 67.3%, respectively; p<0.05 vs controls) but it was total in those from TR (82.3%, p=NS vs A; p<0.05 vs hearts from TL and SR). Similarly, IP determined a similar increase of norepinephrine release in A (p<0.001) and in TR (p<0.001, p=NS vs adult). IP was abolished by depletion of myocardial norepinephrine stores by reserpine in all groups. Thus, IP reduces post-ischemic dysfunction in A but not in SL. Moreover, IP was preserved partially in TR and SR and totally in TR. Complete IP maybe due to full restoration of norepinephrine release in response to IP stimulus. PMID:15664731

Abete, P; Testa, G; Galizia, G; Mazzella, F; Della Morte, D; de Santis, D; Calabrese, C; Cacciatore, F; Gargiulo, G; Ferrara, N; Rengo, G; Sica, V; Napoli, C; Rengo, F

2005-01-01

15

Role of ischemic preconditioning in hepatic ischemia-reperfusion injury  

PubMed Central

Background Investigation into less traumatic method of vascular occlusion during liver resection is the actual problem in hepatic surgery because of high level of complications such as liver failure. In this connection, the goal of our study was to determine the optimal model of vascular clamping. The research showed that vascular occlusion with ischemic preconditioning in the mode 5/10/15 the most delicate technique. Methods Forty white giant rabbits were divided randomly into four groups (n=10 in each group). In group I we used continuous Pringle maneuver by 30 min. In group II we used intermittent Pringle maneuver: 15 min of clamping/5 min of unclamping (reperfusion)/15 min of clamping. In group III we used intermittent Pringle maneuver with ischemic precondition: 5 min of ischemia/5 min of reperfusion, 10 min of ischemia/5 min of reperfusion/15 min of ischemia. Group IV (control group) is without hepatic ischemia. All animals were performed a liver biopsy at the end of the surgery. Five rabbits from each group underwent re-laparotomy on day 3 after surgery with biopsy samples being taken for studying reparative processes in liver parenchyma. Results Results of morphometric analysis were the best to illustrate different level of liver injury in the groups. Thus, there were 95.5% damaged hepatocytes after vascular occlusion in hepatic preparations in group I, 70.3% damaged hepatocytes in group II, and 42.3% damaged hepatocytes in group III. There were 5.3% damaged hepatocytes in the control group. Conclusions Vascular occlusion with ischemic preconditioning in the mode 5/10/15 the most delicate technique that does not involve major structural injuries and functional disorders in the remnant liver. Thus, it is amenable to translation into clinical practice and may improve outcomes in liver resection with inflow vascular occlusion.

Boyko, Valeriy V.; Tyshchenko, Oleksandr M.; Skoryi, Denys I.; Kozlova, Tatiana V.; Gorgol, Natalia I.; Volchenko, Igor V.

2014-01-01

16

Age-related reduction of cerebral ischemic preconditioning: myth or reality?  

PubMed Central

Stroke is one of the leading causes of death in industrialized countries for people older than 65 years of age. The reasons are still unclear. A reduction of endogenous mechanisms against ischemic insults has been proposed to explain this phenomenon. The “cerebral” ischemic preconditioning mechanism is characterized by a brief episode of ischemia that renders the brain more resistant against subsequent longer ischemic events. This ischemic tolerance has been shown in numerous experimental models of cerebral ischemia. This protective mechanism seems to be reduced with aging both in experimental and clinical studies. Alterations of mediators released and/or intracellular pathways may be responsible for age-related ischemic preconditioning reduction. Agents able to mimic the “cerebral” preconditioning effect may represent a new powerful tool for the treatment of acute ischemic stroke in the elderly. In this article, animal and human cerebral ischemic preconditioning, its age-related difference, and its potential therapeutical applications are discussed. PMID:24204128

Della-Morte, David; Cacciatore, Francesco; Salsano, Elisa; Pirozzi, Gilda; Genio, Maria Teresa Del; D'Antonio, Iole; Gargiulo, Gaetano; Palmirotta, Raffaele; Guadagni, Fiorella; Rundek, Tatjana; Abete, Pasquale

2013-01-01

17

Remote Ischemic Preconditioning (RIPC) Modifies Plasma Proteome in Humans  

PubMed Central

Remote Ischemic Preconditioning (RIPC) induced by brief episodes of ischemia of the limb protects against multi-organ damage by ischemia-reperfusion (IR). Although it has been demonstrated that RIPC affects gene expression, the proteomic response to RIPC has not been determined. This study aimed to examine RIPC induced changes in the plasma proteome. Five healthy adult volunteers had 4 cycles of 5 min ischemia alternating with 5 min reperfusion of the forearm. Blood samples were taken from the ipsilateral arm prior to first ischaemia, immediately after each episode of ischemia as well as, at 15 min and 24 h after the last episode of ischemia. Plasma samples from five individuals were analysed using two complementary techniques. Individual samples were analysed using 2Dimensional Difference in gel electrophoresis (2D DIGE) and mass spectrometry (MS). Pooled samples for each of the time-points underwent trypsin digestion and peptides generated were analysed in triplicate using Liquid Chromatography and MS (LC-MS). Six proteins changed in response to RIPC using 2D DIGE analysis, while 48 proteins were found to be differentially regulated using LC-MS. The proteins of interest were involved in acute phase response signalling, and physiological molecular and cellular functions. The RIPC stimulus modifies the plasma protein content in blood taken from the ischemic arm in a cumulative fashion and evokes a proteomic response in peripheral blood. PMID:23139772

Hepponstall, Michele; Ignjatovic, Vera; Binos, Steve; Monagle, Paul; Jones, Bryn; Cheung, Michael H. H.; d'Udekem, Yves; Konstantinov, Igor E.

2012-01-01

18

Inhalational anesthetics as neuroprotectants or chemical preconditioning agents in ischemic brain  

Microsoft Academic Search

This review will focus on inhalational anesthetic neuroprotection during cerebral ischemia and inhalational anesthetic preconditioning before ischemic brain injury. The limitations and challenges of past and current research in this area will be addressed before reviewing experimental and clinical studies evaluating the effects of inhalational anesthetics before and during cerebral ischemia. Mechanisms underlying volatile anesthetic neuroprotection and preconditioning will also

Hideto Kitano; Jeffrey R Kirsch; Patricia D Hurn; Stephanie J Murphy

2007-01-01

19

Remote ischemic preconditioning in patients with intermittent claudication  

PubMed Central

OBJECTIVE: Remote ischemic preconditioning (RIPC) is a phenomenon in which a short period of sub-lethal ischemia in one organ protects against subsequent bouts of ischemia in another organ. We hypothesized that RIPC in patients with intermittent claudication would increase muscle tissue resistance to ischemia, thereby resulting in an increased ability to walk. METHODS: In a claudication clinic, 52 ambulatory patients who presented with complaints of intermittent claudication in the lower limbs associated with an absent or reduced arterial pulse in the symptomatic limb and/or an ankle-brachial index <0.90 were recruited for this study. The patients were randomly divided into three groups (A, B and C). All of the patients underwent two tests on a treadmill according to the Gardener protocol. Group A was tested first without RIPC. Group A was subjected to RIPC prior to the second treadmill test. Group B was subjected to RIPC prior to the first treadmill test and then was subjected to a treadmill test without RIPC. In Group C (control group), both treadmill tests were performed without RIPC. The first and second tests were conducted seven days apart. Brazilian Clinical Trials: RBR-7TF6TM. RESULTS: Group A showed a significant increase in the initial claudication distance in the second test compared to the first test. CONCLUSION: RIPC increased the initial claudication distance in patients with intermittent claudication; however, RIPC did not affect the total walking distance of the patients. PMID:23778346

Saes, Glauco Fernandes; Zerati, Antonio Eduardo; Wolosker, Nelson; Ragazzo, Luciana; Rosoky, Ruben Miguel Ayzin; Ritti-Dias, Raphael Mendes; Cucato, Gabriel Grizzo; Chehuen, Marcelo; Farah, Breno Quintella; Puech-Leao, Pedro

2013-01-01

20

Sarcolemmal Blebs and Osmotic Fragility as Correlates of Irreversible Ischemic Injury in Preconditioned Isolated Rabbit Cardiomyocytes  

Microsoft Academic Search

The hypothesis that irreversible ischemic injury is related to sub-sarcolemmal blebbing and an inherent osmotic fragility of the blebs was tested by subjecting isolated control and ischemically preconditioned (IPC) or calyculin A (CalA)-pretreated (protected) rabbit cardiomyocytes to ischemic pelleting followed by resuspension in 340, 170 or 85 mosmol medium containing trypan blue. At time points from 0–240 min, osmotic fragility

Stephen C. Armstrong; Christine L. Shivell; Charles E. Ganote

2001-01-01

21

Ischemic preconditioning enhances integrity of coronary endothelial tight junctions.  

PubMed

Ischemic preconditioning (IPC) is one of the most effective procedures known to protect hearts against ischemia/reperfusion (IR) injury. Tight junction (TJ) barriers occur between coronary endothelial cells. TJs provide barrier function to maintain the homeostasis of the inner environment of tissues. However, the effect of IPC on the structure and function of cardiac TJs remains unknown. We tested the hypothesis that myocardial IR injury ruptures the structure of TJs and impairs endothelial permeability whereas IPC preserves the structural and functional integrity of TJs in the blood-heart barrier. Langendorff hearts from C57BL/6J mice were prepared and perfused with Krebs-Henseleit buffer. Cardiac function, creatine kinase release, and myocardial edema were measured. Cardiac TJ function was evaluated by measuring Evans blue-conjugated albumin (EBA) content in the extravascular compartment of hearts. Expression and translocation of zonula occludens (ZO)-2 in IR and IPC hearts were detected with Western blot. A subset of hearts was processed for the observation of ultra-structure of cardiac TJs with transmission electron microscopy. There were clear TJs between coronary endothelial cells of mouse hearts. IR caused the collapse of TJs whereas IPC sustained the structure of TJs. IR increased extravascular EBA content in the heart and myocardial edema but decreased the expression of ZO-2 in the cytoskeleton. IPC maintained the structure of TJs. Cardiac EBA content and edema were reduced in IPC hearts. IPC enhanced the translocation of ZO-2 from cytosol to cytoskeleton. In conclusion, TJs occur in normal mouse heart. IPC preserves the integrity of TJ structure and function that are vulnerable to IR injury. PMID:22846574

Li, Zhao; Jin, Zhu-Qiu

2012-08-31

22

Angiotensin II Removes Kidney Resistance Conferred by Ischemic Preconditioning  

PubMed Central

Ischemic preconditioning (IPC) by ischemia/reperfusion (I/R) renders resistance to the kidney. Strong IPC triggers kidney fibrosis, which is involved in angiotensin II (AngII) and its type 1 receptor (AT1R) signaling. Here, we investigated the role of AngII/AT1R signal pathway in the resistance of IPC kidneys to subsequent I/R injury. IPC of kidneys was generated by 30 minutes of bilateral renal ischemia and 8 days of reperfusion. Sham-operation was performed to generate control (non-IPC) mice. To examine the roles of AngII and AT1R in IPC kidneys to subsequent I/R, IPC kidneys were subjected to either 30 minutes of bilateral kidney ischemia or sham-operation following treatment with AngII, losartan (AT1R blocker), or AngII plus losartan. IPC kidneys showed fibrotic changes, decreased AngII, and increased AT1R expression. I/R dramatically increased plasma creatinine concentrations in non-IPC mice, but not in IPC mice. AngII treatment in IPC mice resulted in enhanced morphological damage, oxidative stress, and inflammatory responses, with functional impairment, whereas losartan treatment reversed these effects. However, AngII treatment in non-IPC mice did not change I/R-induced injury. AngII abolished the resistance of IPC kidneys to subsequent I/R via the enhancement of oxidative stress and inflammatory responses, suggesting that the AngII/AT1R signaling pathway is associated with outcome in injury-experienced kidney. PMID:25243156

Kim, Jee In; Park, Jeen-Woo

2014-01-01

23

Ischemic preconditioning, insulin, and morphine all cause hexokinase redistribution.  

PubMed

Association of hexokinase (HK) with mitochondria preserves mitochondrial integrity and is an important mechanism by which cancer cells are protected against hypoxic conditions. Maintenance of mitochondrial integrity also figures prominently as a major characteristic of many cardioprotective manipulations. In this study, we provide evidence that cardioprotective interventions may promote HK redistribution from the cytosol to the mitochondria in the heart. Isolated Langendorff-perfused rat hearts (n = 6/group) were subjected to normoxic perfusion (control, Con), three 5-min ischemia-reperfusion periods (ischemic preconditioning, IPC), 1 U/l insulin (Ins), or 1 microM morphine (Mor). Hearts were immediately homogenized and centrifuged to obtain whole cell, cytosolic, and mitochondrial fractions. HK, lactate dehydrogenase (LDH), and citrate synthase (CS) enzyme activities were determined. No change in LDH or CS present in the cytosol fraction relative to whole cell activity was observed with any of the cardioprotective interventions. By contrast, HK present in the cytosol fraction relative to whole cell activity decreased significantly (P < 0.05) with all cardioprotective interventions, from 0.58 +/- 0.03 (Con) to 0.46 +/- 0.04 (IPC), 0.41 +/- 0.01 (Ins), and 0.45 +/- 0.02 (Mor). In addition, HK relative to CS activity in the mitochondrial fraction increased significantly with cardioprotection, from 0.15 +/- 0.001 (Con) to 0.21 +/- 0.002 (IPC), 0.18 +/- 0.003 (Ins), and 0.21 +/- 0.005 (Mor). Our novel data suggest that well-known cardioprotective interventions share a common end-effector mechanism of cytosolic HK translocation. Association of HK with mitochondria may promote inhibition of the mitochondrial permeability transition pore and thereby reduce cell death and apoptosis. PMID:15764678

Zuurbier, Coert J; Eerbeek, Otto; Meijer, Alfred J

2005-07-01

24

The Role of Erythropoetin in Ischemic Preconditioning, Postconditioning, and Regeneration of the Brain after Ischemia  

Microsoft Academic Search

Analysis of published data shows that erythropoietin plays an important role in controlling the tolerance of the brain to\\u000a the actions of ischemia and reperfusion. This cytokine has a role in ischemic preconditioning of the brain and can imitate\\u000a the phenomena of preconditioning and postconditioning. However, it is unclear whether endogenous erythropoietin is involved\\u000a in postconditioning of the brain. Erythropoetin

L. N. Maslov

2011-01-01

25

Remote ischemic preconditioning as treatment for non-ischemic gastrointestinal disorders: Beyond ischemia-reperfusion injury  

PubMed Central

Common gastrointestinal diseases such as radiation enteritis (RE), acute pancreatitis, inflammatory bowel diseases (IBD) and drug-induced hepatotoxicity share pathophysiological mechanisms at the molecular level, mostly involving the activation of many pathways of the immune response, ultimately leading to tissue injury. Increased oxidative stress, inflammatory cytokine release, inflammatory cell infiltration and activation and the up-regulation of inflammatory transcription factors participate in the pathophysiology of these complex entities. Treatment varies in each specific disease, but at least in the cases of RE and IBD immunosuppressors are effective. However, full therapeutic responses are not always achieved. The pathophysiology of ischemia-reperfusion (IR) injury shares many of these mechanisms. Brief and repetitive periods of ischemia in an organ or limb have been shown to protect against subsequent major IR injury in distant organs, a phenomenon called remote ischemic preconditioning (RIP). This procedure has been shown to protect the gut, pancreas and liver by modulating many of the same inflammatory mechanisms. Since RIP is safe and tolerable, and has shown to be effective in some recent clinical trials, I suggest that RIP could be used as a physiologically relevant adjunct treatment for non-ischemic gastrointestinal inflammatory conditions. PMID:24707140

Camara-Lemarroy, Carlos Rodrigo

2014-01-01

26

What Happened if Various Kinds of Postconditioning Working on the Preconditioned Ischemic Skin Flaps  

PubMed Central

Objective: Ischemic pre-conditioning and post-conditioning are useful manipulations to reduce the undesirable effects of ischemia-reperfusion skin flap each. But the impact of post-conditioning on the pre-conditioning skin flap is not manifested. Here we investigated the influence of ischemic post-conditioning in a preconditioned axial pattern skin flap model. Method: We used the skin flap in 40 rabbits and divided them into 5 groups randomly. At first we induced the ischemic pre-conditioning of the flap which was applied by 2 periods of 15 minutes of ischemia/15 minutes of reperfusion cycle. Next post-conditioning was performed by 6 cycles of 10 seconds of repeated ischemia/reperfusion periods at different times of just after the reperfusion,5 minutes after the reperfusion,10 minutes after the reperfusion. The animals were allocated into 5 groups: group 1 (Ischemia Group); group 2: (Pre-conditioning Group); group 3: (Pre-conditioning+ Post-conditioning Group); group 4 (Pre-conditioning+ Post-conditioning 5 minutes later Group); group5 (Pre-conditioning+ Post-conditioning 10 minutes later). The neutrophil count was assessed with histologic analysis before the dissection of the skin flap. Flap viability was assessed 1 week after the operation, and surviving flap area was recorded as a percentage of the whole flap area. LSD test was used for statistical analysis among different groups to evaluate the effects of ischemic pre-conditioning against ischemia. Result: Among the varying groups, the neutrophil count varied: Group 1 was50.12±5.91; Group 2, 30.00±2.00, and Group 3, 18.87±3; Group 4, 22.50±1.92; Group 5, 30.12±1.88.The mean± SD surviving areas of the flaps for groups 1, 2, 3, 4 and 5 were 31.76±4.59, 51.26±3.24,82.18±5.28,66.85±3.87 and 51.13±2.90 respectively. Spearman correlation analysis shows an increase relation between neutrophil count and flap survival rate in the different groups (P <0.05). Conclusion: Ischemic post-conditioning has protective effect on ischemic preconditioned skin flaps, but the post-conditioning should be performed within 5 minutes after the end of ischemia. PMID:24147150

Huang, Lin

2013-01-01

27

Some mechanisms of the protective effect of ischemic preconditioning on rat liver ischemia-reperfusion injury  

PubMed Central

Ischemia-reperfusion (I/R) injury is a multifactorial process that affects graft function after liver transplantation. An understanding of the mechanisms involved in I/R injury is essential for the design of therapeutic strategies to improve the outcome of liver transplantation. The generation of reactive oxygen species subsequent to reoxygenation inflicts tissue damage and initiates a cascade of deleterious cellular responses, leading to inflammation, cell death, and ultimate organ failure. Increasing experimental evidence has suggested that Kupffer cells and T-cells mediate activation of neutrophil inflammatory responses. Activated neutrophils infiltrate the injured liver in parallel with increased expression of adhesion molecules on endothelial cells. The heme oxygenase system is among the most critical of the cytoprotective mechanisms activated during cellular stress, exerting antioxidant and anti-inflammatory functions, modulating the cell cycle, and maintaining the microcirculation. Finally, the activation of toll-like receptors on Kupffer cells may play a fundamental role in exploring new therapeutic strategies based on the concept that hepatic I/R injury represents a case for host “innate” immunity. In the present study, there was a significant decrease in hepatic activity of glycogen in the I/R group as compared with corresponding values in the control group. On the other hand, there was a significant increase in the hepatic activity of glycogen in the I/R-IP (ischemic preconditioning) group as compared with corresponding values in the I/R group. PMID:25382983

Adam, Abdel Nasser Ismail

2014-01-01

28

Enhanced cell volume regulation: a key mechanism in local and remote ischemic preconditioning.  

PubMed

We have previously shown that ischemic preconditioning (IPC) protection against necrosis in whole hearts and in both fresh and cultured cardiomyocytes, as well as the improved regulatory volume decrease to hypoosmotic swelling in cardiomyocytes, is abrogated through Cl(-) channel blockade, pointing to a role for enhanced cell volume regulation in IPC. To further define this cardioprotective mechanism, cultured rabbit ventricular cardiomyocytes were preconditioned either by 10-min simulated ischemia (SI) followed by 10-min simulated reperfusion (SR), by 10-min exposure/10-min washout of remote IPC (rIPC) plasma dialysate (from rabbits subjected to repetitive limb ischemia), or by adenoviral transfection with the constitutively active PKC-? gene. These interventions were done before cardiomyocytes were subjected to either 60- or 75-min SI/60-min SR to assess cell necrosis (by trypan blue staining), 30-min SI to assess ischemic cell swelling, or 30-min hypoosmotic (200 mosM) stress to assess cell volume regulation. Necrosis after SI/SR and both SI- and hypoosmotic stress-induced swelling was reduced in preconditioned cardiomyocytes compared with control cardiomyocytes (neither preconditioned nor transfected). These effects on necrosis and cell swelling were blocked by either Cl(-) channel blockade or dominant negative knockdown of inwardly rectifying K(+) channels with adenoviruses, suggesting that Cl(-) and K(+) movements across the sarcolemma are critical for cell volume regulation and, thereby, cell survival under hypoxic/ischemic conditions. Our results define enhanced cell volume regulation as a key common mechanism of cardioprotection by preconditioning in cardiomyocytes. PMID:24760980

Diaz, Roberto J; Harvey, Kordan; Boloorchi, Azadeh; Hossain, Taneya; Hinek, Alina; Backx, Peter H; Wilson, Gregory J

2014-06-15

29

Delayed Energy Protection of Ischemic Preconditioning on Hepatic Ischemia\\/Reperfusion Injury in Rats  

Microsoft Academic Search

Background: Hepatic ischemia\\/reperfusion (IR) injuries associated with hepatic resections are unresolved problems in the clinical practice. The aim of this study is to elucidate the effect of ischemic preconditioning (IPC) on the energy charge (EC) and related mechanisms at the late phase of hepatic IR injury. Methods: 30 Wistar rats were randomly divided into sham, IR and IPC groups. The

E. Ofluoglu; M. Kerem; H. Pasaoglu; N. Turkozkan; I. Seven; A. Bedirli; T. Utku Yilmaz

2006-01-01

30

Ischemic preconditioning and preinfarction angina in the clinical arena  

Microsoft Academic Search

In animals, brief episodes of ischemia before a total coronary occlusion protect the heart and result in a smaller myocardial infarct size. In humans, episodes of angina before acute myocardial infarction might also confer a preconditioning or protective effect; numerous studies show that preinfarction angina is associated with smaller infarcts. Preinfarction angina is also associated with reductions in ventricular dysfunction,

Robert A Kloner; Shereif H Rezkalla

2004-01-01

31

Remote Ischemic Preconditioning for Prevention of Contrast-induced Acute Kidney Injury in Diabetic Patients.  

PubMed

Introduction. There are some clinical trials showing that short-term ischemia in one organ can protect different organs against higher intensity and longer ischemic insult. We designed a study to assess whether remote ischemic preconditioning (RIPC) on one organ can decrease the rate of contrast-induced acute kidney injury (AKI) in diabetic patients who undergo coronary artery angiography (CAA). Materials and Methods. This randomized control trial included 96 diabetic patients who were candidates for CAA. Exclusion criteria were congestive heart failure and complications during CAA. All of the patients received 1000 mL of normal saline before CAA. The RIPC group underwent 3 cycles of 5-minute ischemia in their right arm. Serum creatinine was measured before and 24 hours after CAA. Results. Contrast-induced AKI was reported in 5 cases in the control group and 1 case in the RIPC group (P = .13, odds ratio, 5.4). The differences in serum creatinine level before and after the procedure was significantly lower in RIPC group than that in the control group (P = .04, odds ratio, 0.08). Serum creatinine rise significantly correlated with contrast dose (P = .02) and a history of hypertension (P = .02) in both groups. Conclusions. Ischemic preconditioning had a protective effect on contrast-induced AKI in our study. Since this method is harmless and cost effective, further studies on patients with chronic kidney disease is required to evaluate addition of ischemic preconditioning to our clinical practice for prevention of contrast-induced AKI. PMID:25362220

Savaj, Shokoufeh; Savoj, Javad; Jebraili, Ismail; Sezavar, Seyed Hashem

2014-11-01

32

Global gene expression profiling of ischemic preconditioning in the rat retina  

PubMed Central

Purpose To obtain and analyze the gene expression changes after ischemic preconditioning (IPC) in the rat retina. Methods Ischemic damage to the inner retina can be prevented by a short, non-deleterious, ischemic insult of 5 min applied 24 h preceding a full ischemic insult of 60 min; a phenomenon termed tolerance or IPC. The time course of changes in gene expression after induction of IPC was assessed by 22K oligonucleotide microarrays, followed by real-time quantitative polymerase chain reaction (qPCR) validation. Functional pathways of interest were identified by Gene Ontology-term analysis. Results Histology confirmed that IPC induction by 5 min of retinal ischemia results in a complete protection against the neurodegenerative effects of a 60 min ischemic period applied 24 or 48 h later. The microarray analysis revealed differential expression of 104 known genes at one or more time points between 1 h and 7 days after IPC. The group of altered genes contained a significant overrepresentation of genes involved in aminoacyl-tRNA synthetase activity (Iars, Lars, Cars, Yars, Gars, Tars), amino acid transport (Slc3a2, Slc6a6, Slc7a1, Slc38a2), regulation of transcription (including Egr1, Egr4, Nr4a1, Nr4a3, c-fos), and cell death (including Anxa1, Trib3). qPCR assays on cDNA of individual animals confirmed the microarray results. Conclusions Endogenous neuroprotection, provoked by ischemic preconditioning is associated with changes in transcript levels of several functionally-related groups of genes. During the time window of effective protection, transcript levels of genes encoding for aminoacyl-tRNA synthetases and for amino acid transport are reduced. These changes suggest that a reduction of translational activity may play a significant role in preconditioning-mediated neuroprotection. PMID:17653046

Dijk, F.; van Soest, S.; Bergen, A.A.B.

2007-01-01

33

PKC Is Required for the Induction of Tolerance by Ischemic and NMDA-Mediated Preconditioning in the Organotypic Hippocampal Slice  

Microsoft Academic Search

Glutamate receptors and calcium have been implicated as triggering factors in the induction of tolerance by ischemic preconditioning (IPC) in the brain. However, little is known about the signal transduction pathway that ensues after the IPC induction pathway. The main goals of the present study were to determine whether NMDA induces preconditioning via a calcium pathway and promotes translocation of

Ami P. Raval; Kunjan R. Dave; Daria Mochly-Rosen; Thomas J. Sick; Miguel A. Perez-Pinzon

34

[Myocardial ischemic preconditioning: pathophysiological mechanisms and prospects of clinical application (a literature review)].  

PubMed

Ischemic preconditioning (IPC, i.e. increase in the organ resistance to a prolonged ischemia which occurs after a brief ischemic challenge) seems to be one of the most powerful endogenous cardioprotective mechanisms known to date. Current data regarding molecular mechanisms of early (classic) IPC as well as the second window of protection are reviewed in the context of the concept of sequential three-staged development of protective effect. Based on original and published data, possible mechanisms of remote IPC are considered. The review comprises current ideas of existence of the IPC clinical correlates and its use in clinic. PMID:11452804

Petrishchev, N N; Shliakhto, E V; Vlasov, T D; Galagudza, M M

2001-05-01

35

Electroacupuncture preconditioning reduces cerebral ischemic injury via BDNF and SDF-1? in mice  

PubMed Central

Background This study was designed to determine if electroacupuncture (EA) preconditioning improves tissue outcome and functional outcome following experimentally induced cerebral ischemia in mice. In addition, we investigated whether the expression of brain-derived neurotrophic factor (BDNF) and stromal cell derived factor-1? (SDF-1?) and infarct volume were related with improvement in neurological and motor function by interventions in this study. Methods After treatment with EA at the acupoints ‘Baihui (GV20)’ and ‘Dazhui (GV14)’ for 20 min, BDNF was assessed in the cortical tissues based on Western blot and the SDF-1? and vascular endothelial growth factor (VEGF) levels in the plasma determined by ELISA. To assess the protective effects of EA against ischemic injury, the mice received once a day 20 min EA preconditioning for three days prior to the ischemic event. Focal cerebral ischemia was then induced by photothrombotic cortical ischemia. Infarct volumes, neurobehavioral deficit and motor deficit were evaluated 24 h after focal cerebral ischemia. Results The expression of BDNF protein increased significantly from 6 h, reaching a plateau at 12 h after the end of EA treatment in the cerebral cortex. Furthermore, SDF-1?, not VEGF, increased singnificantly from 12 h to 48 h after EA stimulation in the plasma. Moreover, EA preconditioning reduced the infarct volume by 43.5% when compared to control mice at 24 h after photothrombotic cortical ischemia. Consistent with a smaller infarct size, EA preconditioning showed prominent improvement of neurological function and motor function such as vestibule-motor function, sensori-motor function and asymmetric forelimb use. The expression of BDNF colocalized within neurons and SDF-1? colocalized within the cerebral vascular endothelium was observed throughout the ischemic cortex by EA. Conclusions Pretreatment with EA increased the production of BDNF and SDF-1?, which elicited protective effects against focal cerebral ischemia. These results suggest a novel mechanism of EA pretreatment-induced tolerance against cerebral ischemic injury. PMID:23356671

2013-01-01

36

Acute bioenergetic intervention or pharmacological preconditioning protects neuron against ischemic injury  

PubMed Central

Although acute ischemic stroke has high mortality and morbidity rate but yet still has very limited treatment. In this study we have tested the concept of neuron protection by acute bioenergetic intervention or by pharmacological preconditioning with natural antioxidants. Adenosine triphosphate (ATP), pentobarbital, and suramin were encapsulated in pH-sensitive liposomes and used as bioenergy stabilizer. We induced ATP depletion model by incubating cells with media added with ATP-depleting agents for 2 hours. Treatment with bioenergy stabilizer started 10-min post inducing of ATP-depletion. The acute treatment with bioenergy stabilizer significantly increased cell viability in neuro-2a cells. In searching for a pharmacological preconditioning candidate for reducing ischemic injury, we tested cocoa-derived flavanols using bilateral common carotid artery occlusion (BCCAO). We pretreated mice with cocoa-derived flavanols (75 mg/kg) or water orally for 7 days and subjected mice for 12 minutes BCCAO. At 7 days post-ischemia, the number of surviving hippocampal CA1 neurons was significantly higher in the treated mice than in the water-treated controls. The protection from cocoa-derived flavanols was found associated with increased total antioxidant capacity in the brain. Our results indicate that for reducing acute ischemic injury bioenergetic intervention using advanced drug delivery tools is conceptually feasible, and for reducing reperfusion related secondary injury pharmacological preconditioning may provide significant protection. PMID:24285991

Liu, Shimin; Zhen, Gehua; Li, Rung-chi; Dore, Sylvain

2013-01-01

37

Exercise Training Preserves Ischemic Preconditioning in Aged Rat Hearts by Restoring the Myocardial Polyamine Pool  

PubMed Central

Background. Ischemic preconditioning (IPC) strongly protects against myocardial ischemia reperfusion (IR) injury. However, IPC protection is ineffective in aged hearts. Exercise training reduces the incidence of age-related cardiovascular disease and upregulates the ornithine decarboxylase (ODC)/polyamine pathway. The aim of this study was to investigate whether exercise can reestablish IPC protection in aged hearts and whether IPC protection is linked to restoration of the cardiac polyamine pool. Methods. Rats aging 3 or 18 months perform treadmill exercises with or without gradient respectively for 6 weeks. Isolated hearts and isolated cardiomyocytes were exposed to an IR and IPC protocol. Results. IPC induced an increase in myocardial polyamines by regulating ODC and spermidine/spermine acetyltransferase (SSAT) in young rat hearts, but IPC did not affect polyamine metabolism in aged hearts. Exercise training inhibited the loss of preconditioning protection and restored the polyamine pool by activating ODC and inhibiting SSAT in aged hearts. An ODC inhibitor, ?-difluoromethylornithine, abolished the recovery of preconditioning protection mediated by exercise. Moreover, polyamines improved age-associated mitochondrial dysfunction in vitro. Conclusion. Exercise appears to restore preconditioning protection in aged rat hearts, possibly due to an increase in intracellular polyamines and an improvement in mitochondrial function in response to a preconditioning stimulus.

Wang, Weiwei; Zhang, Hao; Xue, Guo; Zhang, Weihua; Wang, Lina; Lu, Fanghao; Li, Hongzhu; Bai, Shuzhi; Lin, Yan; Lou, Yu; Xu, Changqing; Zhao, Yajun

2014-01-01

38

Roles of collateral arterial flow and ischemic preconditioning in protection of acutely ischemic myocardium.  

PubMed

The extent and rate at which necrosis develops in experimental acute myocardial infarction in the dog heart is presented together with an analysis of the role played by protective mechanisms in myocyte death. Preconditioning with ischemia delays but does not prevent myocyte death. Arterial collateral flows exceeding 30% of control flow essentially prevent myocyte death, while lesser amounts of collateral flow delay myocyte death to a variable extent. Flows of <0.09mlmin(-1)g(-1) wet exert no protective effect. Cell death occurs as quickly as it does with zero flow. Electrocardiography provides a means of detection of the preconditioned state in the dog heart in that the amount of ST elevation observed during the preconditioning episode is reduced during subsequent episodes of ischemia. Also, marked depression of arterial collateral flow can be detected by an increase in the duration of the QRS segment. PMID:24952922

Jennings, Robert B; Wagner, Galen S

2014-01-01

39

The Effects of Remote Ischemic Preconditioning and N-Acetylcysteine with Remote Ischemic Preconditioning in Rat Hepatic Ischemia Reperfusion Injury Model  

PubMed Central

Background. Remote ischemic preconditioning (RIP) and pharmacological preconditioning are the effective methods that can be used to prevent ischemia reperfusion (IR) injury. The aim of this study was to evaluate the effects of RIP and N-Acetylcysteine (NAC) with RIP in the rat hepatic IR injury model. Materials and Methods. 28 rats were divided into 4 groups. Group I (sham): only laparotomy was performed. Group II (IR): following 30 minutes of hepatic pedicle occlusion, 4 hours of reperfusion was performed. Group III (RIP + IR): following 3 cycles of RIP, hepatic IR was performed. Group IV (RIP + NAC + IR): following RIP and intraperitoneal administration of NAC (150?mg/kg), hepatic IR was performed. All the rats were sacrificed after blood samples were taken for the measurements of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels and liver was processed for conventional histopathology. Results. The hepatic histopathological injury scores of RIP + IR and RIP + NAC + IR groups were significantly lower than IR group (P = 0.006, P = 0.003, resp.). There were no significant differences in AST and ALT values between the IR, RIP + IR, and RIP + NAC + IR groups. Conclusions. In the present study, it was demonstrated histopathologically that RIP and RIP + NAC decreased hepatic IR injury significantly. PMID:24511549

Uysal, Ali Ihsan; Ozkardesler, Sevda; Ergur, Bekir Ugur; Guneli, Ensari; Kume, Tuncay; Unal Togrul, Belgin

2014-01-01

40

Ischemic Preconditioning Protects against Spinal Cord Ischemia-Reperfusion Injury in Rabbits by Attenuating Blood Spinal Cord Barrier Disruption  

PubMed Central

Ischemic preconditioning has been reported to protect against spinal cord ischemia-reperfusion (I-R) injury, but the underlying mechanisms are not fully understood. To investigate this, Japanese white rabbits underwent I-R (30 min aortic occlusion followed by reperfusion), ischemic preconditioning (three cycles of 5 min aortic occlusion plus 5 min reperfusion) followed by I-R, or sham surgery. At 4 and 24 h following reperfusion, neurological function was assessed using Tarlov scores, blood spinal cord barrier permeability was measured by Evan’s Blue extravasation, spinal cord edema was evaluated using the wet-dry method, and spinal cord expression of zonula occluden-1 (ZO-1), matrix metalloproteinase-9 (MMP-9), and tumor necrosis factor-? (TNF-?) were measured by Western blot and a real-time polymerase chain reaction. ZO-1 was also assessed using immunofluorescence. Spinal cord I-R injury reduced neurologic scores, and ischemic preconditioning treatment ameliorated this effect. Ischemic preconditioning inhibited I-R-induced increases in blood spinal cord barrier permeability and water content, increased ZO-1 mRNA and protein expression, and reduced MMP-9 and TNF-? mRNA and protein expression. These findings suggest that ischemic preconditioning attenuates the increase in blood spinal cord barrier permeability due to spinal cord I-R injury by preservation of tight junction protein ZO-1 and reducing MMP-9 and TNF-? expression. PMID:23685868

Fang, Bo; Li, Xiao-Man; Sun, Xi-Jia; Bao, Na-Ren; Ren, Xiao-Yan; Lv, Huang-Wei; Ma, Hong

2013-01-01

41

Genomic analysis of ischemic preconditioning in adult rat hippocampal slice cultures.  

PubMed

Understanding endogenous mechanisms of neuroprotection may have important clinical applications. It is well established that brain tissue becomes more resistant to ischemic injury following a sublethal ischemic insult. This process, called ischemic preconditioning (IPC), can be induced in adult rat hippocampal slice cultures by a brief oxygen-glucose deprivation (OGD) [Hassen, G.W., Tian, D., Ding, D., Bergold, P.J., 2004. A new model of ischemic preconditioning using young adult hippocampal slice cultures. Brain Res. Brain Res. Protoc. 13, 135-143]. We have analyzed the changes in gene expression brought about by IPC in this model in order to understand the mechanisms involved. Total RNA was isolated at different time points following a brief OGD (3, 6 and 12 h) and used to probe genome-wide expression microarrays. Genes were identified that were significantly up- or down-regulated relative to controls. We placed genes that were differentially expressed into statistically significant groups based on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and gene ontology (GO) terms. Genes involved in signal transduction, transcription, and oxidative phosphorylation are differentially expressed at each time point. The analysis demonstrates that alterations in signaling pathways (TGF-beta, Wnt, MAPK, ErbB, Toll-like receptor, JAK-STAT, VEGF) consistently accompany IPC. RT-PCR was used to confirm that members of these signaling pathways are regulated as predicted by the microarray analysis. We verified that protein translation following OGD is necessary for IPC. We also found that blocking the NMDA receptor during OGD does not significantly inhibit IPC in this model or produce large changes in gene expression. Our data thus suggests that changes in signaling pathways and their down-stream targets play an important role in triggering endogenous neuroprotection. PMID:19631194

Benardete, Ethan A; Bergold, Peter J

2009-10-01

42

Ischemic preconditioning affects hexokinase activity and HKII in different subcellular compartments throughout cardiac ischemia-reperfusion.  

PubMed

The glycolytic enzyme hexokinase (HK) is suggested to play a role in ischemic preconditioning (IPC). In the present study we determined how ischemic preconditioning affects HK activity and HKI and HKII protein content at five different time points and three different subcellular fractions throughout cardiac ischemia-reperfusion. Isolated Langendorff-perfused rat hearts (10 groups of 7 hearts each) were subjected to 35 min ischemia and 30 min reperfusion (control groups); the IPC groups were pretreated with 3 times 5-min ischemia. IPC was without effect on microsomal HK activity, and only decreased cytosolic HK activity at 35 min ischemia, which was mimicked by decreased cytosolic HKII, but not HKI, protein content. In contrast, mitochondrial HK activity at baseline and during reperfusion was elevated by IPC, without changes during ischemia. No effect of IPC on mitochondrial HK I protein content was observed. However, mitochondrial HK II protein content during reperfusion was augmented by IPC, albeit not following the IPC stimulus. It is concluded that IPC results in decreased cytosolic HK activity during ischemia that could be explained by decreased HKII protein content. IPC increased mitochondrial HK activity before ischemia and during reperfusion that was only mimicked by increased HK II protein content during reperfusion. IPC was without effect on the phosphorylation status of HK before ischemia. We conclude that IPC is associated with 1) a biphasic response of increased mitochondrial HK activity before and after ischemia, 2) decreased cytosolic HK activity during ischemia, and 3) cellular redistribution of HKII but not HKI. PMID:19228992

Gürel, Ebru; Smeele, Kirsten M; Eerbeek, Otto; Koeman, Anneke; Demirci, Cihan; Hollmann, Markus W; Zuurbier, Coert J

2009-06-01

43

[The effect of ischemic preconditioning on early death in acute Q-wave myocardial infarction].  

PubMed

Ischaemic preconditioning is still a laboratory-based phenomenon, not conclusively documented in patients. In this study it was of interest whether there is any beneficial influence of ischemic preconditioning on 30-day in-hospital mortality in patients undergoing acute Q-wave myocardial infarction. All men and women admitted to our ward between December 1994 and July 1996 with their first acute Q-wave myocardial infarction were divided into two groups. I group--29 patients with prodromal angina, defined as chest pain episodes in the 24-hour period before myocardial infarction. II group--25 patients who showed no chest pain before infarction onset. Both groups did not differ statistically in view of age, sex, smoking habits and adjunctive therapy. The use of streptokinase in the I and II group was also similar--in 58.6% and 56% of patients respectively in the first and second group. In the I group there was no fatal outcome, all 5 death cases occurred in the II group. The results are statistically significant and suggest lower in-hospital mortality in Q-wave myocardial infarction patients with previous ischaemic preconditioning. PMID:9557116

Stoch, K

1997-01-01

44

Notch signaling activation contributes to cardioprotection provided by ischemic preconditioning and postconditioning  

PubMed Central

Background Notch signaling is known to be activated following myocardial ischemia, but its role in cardioprotection provided by ischemic preconditioning (IPC) and ischemic postconditioning (IPost) remains unclear. Methods Lentiviral vectors were constructed to overexpress or knockdown N1ICD in H9c2 cardiomyocyte and rat heart exposed to ischemia reperfusion injury (IRI), IPC or IPost. Results Notch1 signaling was activated during myocardial IPC and IPost, and could enhance cell viability and inhibit apoptosis. Furthermore, activated Notch1 signaling stabilized mitochondrial membrane potential and reduced reactive oxygen species induced by IRI. The cardioprotection provided by activated Notch1 signaling resembled that of IPC and IPost, which was related to Stat3 activation and regulation of apoptosis related proteins. Furthermore, in langendorff heart perfusion model, activated Notch1 signaling restored cardiac function, decreased lactate dehydrogenase release and limited infarct size after myocardial ischemia. Conclusions: Notch1 signaling is activated and mediates cardioprotection provided by IPC and Ipost. Notch1 signaling may represent a potential new pharmacologic mimic for cardioprotection of ischemic heart disease. PMID:24098939

2013-01-01

45

Modification of the Hepatic Mitochondrial Proteome in Response to Ischemic Preconditioning following Ischemia-Reperfusion Injury of the Rat Liver  

Microsoft Academic Search

Background\\/Aim: Ischemic preconditioning (IPC) may reduce hepatic ischemia-reperfusion (IR) injury, but efficacy of IPC on mitochondrial proteome is not demonstrated. We investigated how IPC modifies the mitochondrial proteome after IR injury. Methods: Rats were subjected to 25 min of portal triad crossclamping (IR group, n = 8). In the IPC group (n = 8), 10 min of temporal portal triad

R. Oshima; H. Nakano; M. Katayama; J. Sakurai; W. Wu; S. Koizumi; T. Asano; T. Watanabe; T. Asakura; T. Ohta; T. Otsubo

2008-01-01

46

Conventional, but not remote ischemic preconditioning, reduces iNOS transcription in liver ischemia/reperfusion  

PubMed Central

AIM: To study the effects of preconditioning on inducible nitric oxide synthase (iNOS) and interleukin 1 (IL-1) receptor transcription in rat liver ischemia/reperfusion injury (IRI). METHODS: Seventy-two male rats were randomized into 3 groups: the one-hour segmental ischemia (IRI, n = 24) group, the ischemic preconditioning (IPC, n = 24) group or the remote ischemic preconditioning (R-IPC, n = 24) group. The IPC and R-IPC were performed as 10 min of ischemia and 10 min of reperfusion. The iNOS and the IL-1 receptor mRNA in the liver tissue was analyzed with real time PCR. The total Nitrite and Nitrate (NOx) in continuously sampled microdialysate (MD) from the liver was analyzed. In addition, the NOx levels in the serum were analyzed. RESULTS: After 4 h of reperfusion, the iNOS mRNA was significantly higher in the R-IPC (?Ct: 3.44 ± 0.57) group than in the IPC (?Ct: 5.86 ± 0.82) group (P = 0.025). The IL-1 receptor transcription activity was reduced in the IPC group (?Ct: 1.88 ± 0.53 to 4.81 ± 0.21), but not in the R-IPC group, during reperfusion (P = 0.027). In the MD, a significant drop in the NOx levels was noted in the R-IPC group (12.3 ± 2.2 to 4.7 ± 1.2 ?mol/L) at the end of ischemia compared with the levels in early ischemia (P = 0.008). A similar trend was observed in the IPC group (11.8 ± 2.1 to 6.4 ± 1.5 ?mol/L), although this difference was not statistically significant. The levels of NOx rose quickly during reperfusion in both groups. CONCLUSION: IPC, but not R-IPC, reduces iNOS and IL-1 receptor transcription during early reperfusion, indicating a lower inflammatory reaction. NOx is consumed in the ischemic liver lobe. PMID:25071345

Bjornsson, Bergthor; Winbladh, Anders; Bojmar, Linda; Sundqvist, Tommy; Gullstrand, Per; Sandstrom, Per

2014-01-01

47

Dystrophin proteolysis: a potential target for MMP-2 and its prevention by ischemic preconditioning.  

PubMed

Dystrophin is responsible for the mechanical stabilization of the sarcolemma, and it has been shown that it is one of the most sensitive proteins to ischemic injury. However, the enzyme responsible for this proteolysis is still unknown. Isolated rabbit hearts were subjected to 30 min of global ischemia with and without reperfusion (180 min) to determine whether dystrophin is cleaved by matrix metalloproteinase (MMP)-2 during acute ischemia and whether ischemic preconditioning (PC) prevents dystrophin breakdown through MMP-2 inhibition. The activity of MMP-2 was evaluated by zymography and using doxycycline as an inhibitor. Also, to stimulate MMP-2 activity without ischemia, SIN-1 was administered in the absence and presence of doxycycline. Finally, we considered the PC effect on MMP-2 activity and dystrophin expression. The dystrophin level decreased during ischemia, reaching 21% of control values (P < 0.05), but the spectrin level remained unchanged. MMP-2 activity increased 71% during ischemia compared with control values (P < 0.05). Doxycycline administration before ischemia prevented dystrophin breakdown. In normoxic hearts, SIN-1 increased thiobarbituric acid-reactive substances by 33% (P < 0.05) and MMP-2 activity by 36% (P < 0.05) and significantly reduced the dystrophin level to 23% of control values (P < 0.05). PC significantly prevented dystrophin breakdown by inhibiting MMP-2 activity, and the dystrophin level reached 89% of control values (P < 0.05). In conclusion, MMP-2 could be responsible for the proteolysis of dystrophin. Thus, dystrophin emerges as a possible novel substrate for MMP-2 in the context of ischemic injury. Furthermore, our results demonstrate that ischemic PC prevents dystrophin breakdown most likely by inhibiting MMP-2 activity. PMID:24791785

Buchholz, Bruno; Perez, Virginia; Siachoque, Nadezda; Miksztowicz, Verónica; Berg, Gabriela; Rodríguez, Manuel; Donato, Martín; Gelpi, Ricardo J

2014-07-01

48

Remote ischemic preconditioning to reduce contrast-induced nephropathy: study protocol for a randomized controlled trial  

PubMed Central

Background Despite the increasing use of pre- and posthydration protocols and low-osmolar instead of high-osmolar iodine-containing contrast media, the incidence of contrast-induced nephropathy (CIN) is still significant. There is evidence that contrast media cause ischemia-reperfusion injury of the medulla. Remote ischemic preconditioning (RIPC) is a non-invasive, safe, and low-cost method to reduce ischemia-reperfusion injury. Methods The RIPCIN study is a multicenter, single-blinded, randomized controlled trial in which 76 patients at risk of CIN will receive standard hydration combined with RIPC or hydration with sham preconditioning. RIPC will be applied by four cycles of 5 min ischemia and 5 min reperfusion of the forearm by inflating a blood pressure cuff at 50 mmHg above the actual systolic pressure. The primary outcome measure will be the change in serum creatinine from baseline to 48 to 72 h after contrast administration. Discussion A recent pilot study reported that RIPC reduced the incidence of CIN after coronary angioplasty. The unusual high incidence of CIN in this study is of concern and limits its generalizability. Therefore, we propose a randomized controlled trial to study whether RIPC reduces contrast-induced kidney injury in patients at risk for CIN according to the Dutch guidelines. Trial registration Current Controlled Trials ISRCTN76496973 PMID:24721127

2014-01-01

49

Cardiac proteomic responses to ischemia-reperfusion injury and ischemic preconditioning.  

PubMed

Cardiac ischemia and ischemia-reperfusion (I/R) injury are major contributors to morbidity and mortality worldwide. Pathological mechanisms of I/R and the physiological mechanisms of ischemic preconditioning (IPC), which is an effective cardiac protective response, have been widely investigated in the last decade to search for means to prevent or treat this disease. Proteomics is a powerful analytical tool that has provided important information to identify target proteins and understand the underlying mechanisms of I/R and IPC. Here, we review the application of proteomics to I/R injury and IPC to discover target proteins. We analyze the functional meaning of the accumulated data on hundreds of proteins using various bioinformatics applications. In addition, we review exercise-induced proteomic alterations in the heart to understand the potential cardioprotective role of exercise against I/R injury. Further developments in the proteomic field that target specialized proteins will yield new insights for optimizing therapeutic targets and developing a wide range of therapeutic agents against ischemic heart disease. PMID:21501017

Kim, Hyoung Kyu; Thu, Vu Thi; Heo, Hye-Jin; Kim, Nari; Han, Jin

2011-04-01

50

[Early ischemic preconditioning against focal transient and permanent brain ischemia in rats: role of collateral circulation].  

PubMed

We hypothesize that early ischemic preconditioning (IPC) can afford protection against focal brief and prolonged cerebral ischemia with subsequent reperfusion as well as permanent brain ischemia in rats by amelioration of regional cerebral blood flow. Adult male Wistar rats (n=97) were subjected to transient (30 and 60 minutes) and permanent middle cerebral artery (MCA) occlusion. IPC protocol consisted of two episodes of 5-min common carotid artery occlusion + 5-min reperfusion prior to test ischemia either followed by 48 hours of reperfusion or not. Triphenyltetrazolium chloride and Evans blue were used for delineation of infarct size and anatomical area at risk (comprises ischemic penumbra and ischemic core), respectively. Blood flow in the MCA vascular bed was measured with use of Doppler ultrasound. The IPC resulted in significant infarct size limitation in both transient and permanent MCA occlusion. Importantly, IPC caused significant reduction of area at risk after 30 min of focal ischemia as compared to controls [med(min-max) 11.4% (3.59-2 0.35%) vs. 2.47% (0.8-9.31%), p = 0.018] but it failed to influence area at risk after 5 min of ischemia [med(min-max) 7.61% (6.32-10.87%) vs. 8.2% (4.87-9.65%), p > 0.05]. No differences in blood flow were found between IPC and control groups using Doppler ultrasound. This is suggestive of the fact that IPC does not really influence blood flow in the large cerebral arteries such as MCA but it might have some effect on smaller arteries. It seems that, along with well established cytoprotective effects of IPC, IPC-mediated reduction of area at risk by means of improvement in local cerebral blood flow may contribute to infarct size limitation after focal transient and permanent brain ischemia in rats. PMID:21598680

Shmonin, A A; Ba?sa, A E; Mel'nikova, E V; Vavilov, V N; Vlasov, T D

2011-02-01

51

Exploring the Human Plasma Proteome for Humoral Mediators of Remote Ischemic Preconditioning - A Word of Caution  

PubMed Central

Despite major advances in early revascularization techniques, cardiovascular diseases are still the leading cause of death worldwide, and myocardial infarctions contribute heavily to this. Over the past decades, it has become apparent that reperfusion of blood to a previously ischemic area of the heart causes damage in and of itself, and that this ischemia reperfusion induced injury can be reduced by up to 50% by mechanical manipulation of the blood flow to the heart. The recent discovery of remote ischemic preconditioning (RIPC) provides a non-invasive approach of inducing this cardioprotection at a distance. Finding its endogenous mediators and their operative mode is an important step toward increasing the ischemic tolerance. The release of humoral factor(s) upon RIPC was recently demonstrated and several candidate proteins were published as possible mediators of the cardioprotection. Before clinical applicability, these potential biomarkers and their efficiency must be validated, a task made challenging by the large heterogeneity in reported data and results. Here, in an attempt to reproduce and provide more experimental data on these mediators, we conducted an unbiased in-depth analysis of the human plasma proteome before and after RIPC. From the 68 protein markers reported in the literature, only 28 could be mapped to manually reviewed (Swiss-Prot) protein sequences. 23 of them were monitored in our untargeted experiment. However, their significant regulation could not be reproducibly estimated. In fact, among the 394 plasma proteins we accurately quantified, no significant regulation could be confidently and reproducibly assessed. This indicates that it is difficult to both monitor and reproduce published data from experiments exploring for RIPC induced plasma proteomic regulations, and suggests that further work should be directed towards small humoral factors. To simplify this task, we made our proteomic dataset available via ProteomeXchange, where scientists can mine for novel potential targets. PMID:25333471

Helgeland, Erik; Breivik, Lars Ertesvag; Vaudel, Marc; Svendsen, ?yvind Sverre; Garberg, Hilde; Nordrehaug, Jan Erik; Berven, Frode Steingrimsen; Jonassen, Anne Kristine

2014-01-01

52

Remote Ischemic Preconditioning Protects against Liver Ischemia-Reperfusion Injury via Heme Oxygenase-1-Induced Autophagy  

PubMed Central

Background Growing evidence has linked autophagy to a protective role of preconditioning in liver ischemia/reperfusion (IR). Heme oxygenase-1 (HO-1) is essential in limiting inflammation and preventing the apoptotic response to IR. We previously demonstrated that HO-1 is up-regulated in liver graft after remote ischemic preconditioning (RIPC). The aim of this study was to confirm that RIPC protects against IR via HO-1-mediated autophagy. Methods RIPC was performed with regional ischemia of limbs before liver ischemia, and HO-1 activity was inhibited pre-operation. Autophagy was assessed by the expression of light chain 3-II (LC3-II). The HO-1/extracellular signal-related kinase (ERK)/p38/mitogen-activated protein kinase (MAPK) pathway was detected in an autophagy model and mineral oil-induced IR in vitro. Results In liver IR, the expression of LC3-II peaked 12–24 h after IR, and the ultrastructure revealed abundant autophagosomes in hepatocytes after IR. Autophagy was inhibited when HO-1 was inactivated, which we believe resulted in the aggravation of liver IR injury (IRI) in vivo. Hemin-induced autophagy also protected rat hepatocytes from IRI in vitro, which was abrogated by HO-1 siRNA. Phosphorylation of p38-MAPK and ERK1/2 was up-regulated in hemin-pretreated liver cells and down-regulated after treatment with HO-1 siRNA. Conclusions RIPC may protect the liver from IRI by induction of HO-1/p38-MAPK-dependent autophagy. PMID:24914543

Xiong, Xuanxuan; Xu, Yonghua; Zhang, Hai; Huang, Changjun; Tian, Yuan; Jiao, Chengyu; Wang, Xuehao; Li, Xiangcheng

2014-01-01

53

Mitochondrial K ATP channel-dependent and -independent phases of ischemic preconditioning against myocardial infarction in the rat  

Microsoft Academic Search

To obtain insight into the role of the mitochondrial ATP-sensitive K+ (mitoKATP) channel in ischemic preconditioning (PC), we aimed to clarify the mitoKATP channel-dependent phase of PC in two PC protocols with different intervals between PC ischemia and an index ischemia. The\\u000a possible contribution of mitoKATP channel opening to protein kinase C activation in PC was also examined by Western

Yukinaga Nozawa; Tetsuji Miura; Takayuki Miki; Yoshito Ohnuma; Toshiyuki Yano; Kazuaki Shimamoto

2003-01-01

54

Ischemic Preconditioning Decreases Mitochondrial Proton Leak and Reactive Oxygen Species Production in the Postischemic Heart  

PubMed Central

Background Proton leak (H+ leak) dissipates mitochondrial membrane potential (m??) through the reentry of protons into the mitochondrial matrix independent of ATP synthase. Changes in H+ leak may affect reactive oxygen species (ROS) production. We measured H+ leak and ROS production during ischemia-reperfusion and ischemic preconditioning (IPC) and examined how changing mitochondrial respiration affected m?? and ROS production. Materials/Methods Isolated rat hearts (n=6/group) were subjected to either Control-IR or IPC. Rate pressure product (RPP) was measured. Mitochondria were isolated at end reperfusion. Respiration was measured by polarography and titrated with increasing concentrations of malonate (0.5-2mM). m?? was measured using a tetraphenylphosphonium electrode. H+ leak is the respiratory rate required to maintain membrane potential at -150mV in the presence of oligomycin-A Mitochondrial complex III ROS production was measured by fluorometry using Amplex-Red. Results IPC improved recovery of RPP at end reperfusion (63±4% vs. 21±2% in Control-IR, p<0.05). Ischemia-reperfusion caused increased H+ leak (94±12 vs. 31±1 nanomoles O/mg protein/min in Non-Ischemic Control, p<0.05). IPC attenuates these increases (55±9 nanomoles O/mg protein/min, p< 0.05 vs. Control-IR). IPC reduced mitochondrial ROS production compared to Control-IR (31±2 vs. 40±3 nanomoles/mg protein/min, p<0.05). As mitochondrial respiration decreased, m?? and mitochondrial ROS production also decreased. ROS production remained lower in IPC than in Control-IR for all m?? and respiration rates. Conclusions Increasing H+ leak is not associated with increased ROS production. IPC decreases both the magnitude of H+ leak and ROS production after ischemia-reperfusion. PMID:21035133

Quarrie, Ricardo; Cramer, Brandon M.; Lee, Daniel S.; Steinbaugh, Gregory E.; Erdahl, Warren; Pfeiffer, Douglas R.; Zweier, Jay L.; Crestanello, Juan A.

2010-01-01

55

Ischemic preconditioning and atenolol on lung injury after intestinal ischemia and reperfusion in rats.  

PubMed

The aim of this study was evaluate the beta blocker atenolol (AT) and ischemic preconditioning (IPC) strategies for tissue protection against systemic effects of intestinal ischemia (I) and reperfusion (R) injury. Forty-two rats were pretreated with AT (1.5 mg · kg(-1)), 0.9% saline solution (SS; 0.1 mL), or IPC and then subjected to prolonged occlusion of the superior mesenteric artery for 60 minutes leading to I followed or not by 120 minutes of R, according to the group. For IPC, 5 minutes of I prior to 10 minutes of R were established. After this process of I or I-R, the right lung of each animal was adequately prepared for staining with hematoxylin and eosin and subsequent histologic analysis for quantification of inflammatory infiltrate was done. The left lung was frozen and prepared for assessment of oxidative stress by the quantification of thiobarbituric acid-reactivity substances (TBARS). Histologic analysis showed an important inflammatory infiltrate in the I-R + SS (I-R + SS = 4.5), which was significantly (P < .05) reduced by IPC (I-R + IPC = 3.0) or AT (I-R + AT = 3.0). Likewise, the TBARS levels were decreased by both strategies (I-R + SS = 0.63; I-R + IPC = 0.23; I-R + AT = 0.38; P < .05). Our results showed that AT and IPC attenuate pulmonary lesions caused by intestinal I and R process. PMID:25131055

Bonservizi, W G S; Koike, M K; Saurim, R; Felix, G A A; da Silva, S M; Montero, E F S; Taha, M O

2014-01-01

56

Ischemic preconditioning and tacrolimus pretreatment as strategies to attenuate intestinal ischemia-reperfusion injury in mice.  

PubMed

The intestine is highly sensitive to ischemia-reperfusion injury (IRI), a phenomenon occurring in different intestinal diseases. Several strategies to mitigate IRI are in experimental stages; unfortunately, no consensus has been reached about the most appropriate one. We report a protocol to study ischemic preconditioning (IPC) evaluation in mice and to combine IPC and tacrolimus (TAC) pretreatment in a warm ischemia model. Mice were divided into treated (IPC, TAC, and IPC + TAC) and untreated groups before intestinal ischemia. IPC, TAC, and IPC + TAC groups were able to decrease postreperfusion nitrites levels (P < .05). IPC-containing groups had a major beneficial effect by preserving the integrity of the intestinal histology (P < .05) and improving animal survival (P < .002) compared with TAC alone or the untreated group. The IPC + TAC group was the only one that showed significant improvement in lung histological analysis (P < .05). The TAC and IPC + TAC groups down-regulated intestinal expression of interleukin (II)-6 and IL1b more than 10-fold compared with the control group. Although IPC and TAC alone reduced intestinal IRI, the used of a combined therapy produced the most significant results in all the local and distant evaluated parameters. PMID:23953566

Stringa, P; Romanin, D; Lausada, N; Machuca, M; Raimondi, J C; Cabanne, A; Rumbo, M; Gondolesi, G

2013-01-01

57

Cardiac phosphoproteomics during remote ischemic preconditioning: a role for the sarcomeric Z-disk proteins.  

PubMed

Remote ischemic preconditioning (RIPC) induced by brief ischemia/reperfusion cycles of remote organ (e.g., limb) is cardioprotective. The myocardial cellular changes during RIPC responsible for this phenomenon are not currently known. The aim of this work was to identify the activation by phosphorylation of cardiac proteins following RIPC. To achieve our aim we used isobaric tandem mass tagging (TMT) and reverse phase nanoliquid chromatography tandem spectrometry using a Linear Trap Quadropole (LTQ) Orbitrap Velos mass spectrometer. Male C57/Bl6 mice were anesthetized by an intraperitoneal injection of Tribromoethanol. A cuff was placed around the hind limb and inflated at 200?mmHg to prevent blood flow as confirmed by Laser Doppler Flowmetry. RIPC was induced by 4 cycles of 5?min of limb ischemia followed by 5?min of reperfusion. Hearts were extracted for phosphoproteomics. We identified approximately 30 phosphoproteins that were differentially expressed in response to RIPC protocol. The levels of several phosphoproteins in the Z-disk of the sarcomere including phospho-myozenin-2 were significantly higher than control. This study describes and validates a novel approach to monitor the changes in the cardiac phosphoproteome following the cardioprotective intervention of RIPC and prior to index ischemia. The increased level of phosphorylated sarcomeric proteins suggests they may have a role in cardiac signaling during RIPC. PMID:24795895

Abdul-Ghani, Safa; Heesom, Kate J; Angelini, Gianni D; Suleiman, M-Saadeh

2014-01-01

58

Cardiac Phosphoproteomics during Remote Ischemic Preconditioning: A Role for the Sarcomeric Z-Disk Proteins  

PubMed Central

Remote ischemic preconditioning (RIPC) induced by brief ischemia/reperfusion cycles of remote organ (e.g., limb) is cardioprotective. The myocardial cellular changes during RIPC responsible for this phenomenon are not currently known. The aim of this work was to identify the activation by phosphorylation of cardiac proteins following RIPC. To achieve our aim we used isobaric tandem mass tagging (TMT) and reverse phase nanoliquid chromatography tandem spectrometry using a Linear Trap Quadropole (LTQ) Orbitrap Velos mass spectrometer. Male C57/Bl6 mice were anesthetized by an intraperitoneal injection of Tribromoethanol. A cuff was placed around the hind limb and inflated at 200?mmHg to prevent blood flow as confirmed by Laser Doppler Flowmetry. RIPC was induced by 4 cycles of 5?min of limb ischemia followed by 5?min of reperfusion. Hearts were extracted for phosphoproteomics. We identified approximately 30 phosphoproteins that were differentially expressed in response to RIPC protocol. The levels of several phosphoproteins in the Z-disk of the sarcomere including phospho-myozenin-2 were significantly higher than control. This study describes and validates a novel approach to monitor the changes in the cardiac phosphoproteome following the cardioprotective intervention of RIPC and prior to index ischemia. The increased level of phosphorylated sarcomeric proteins suggests they may have a role in cardiac signaling during RIPC. PMID:24795895

Abdul-Ghani, Safa; Heesom, Kate J.; Angelini, Gianni D.; Suleiman, M-Saadeh

2014-01-01

59

CBF changes associated with focal ischemic preconditioning in the spontaneously hypertensive rat  

Microsoft Academic Search

Experimental stroke models exhibit robust protection after prior preconditioning (PC) insults. This study comprehensively examined cerebral blood flow (CBF) responses to permanent middle cerebral artery (MCA) occlusion in spontaneously hypertensive rats preconditioned by noninjurious transient focal ischemia, using [14C]iodoantipyrine autoradiography at varied occlusion intervals. Preconditioning was produced by 10-min occlusion of the MCA and ipsilateral common carotid artery under halothane

Liang Zhao; Thaddeus S Nowak

2006-01-01

60

Unique Transcriptional Profile of Sustained Ligand-Activated Preconditioning in Pre- and Post-Ischemic Myocardium  

PubMed Central

Background Opioidergic SLP (sustained ligand-activated preconditioning) induced by 3–5 days of opioid receptor (OR) agonism induces persistent protection against ischemia-reperfusion (I-R) injury in young and aged hearts, and is mechanistically distinct from conventional preconditioning responses. We thus applied unbiased gene-array interrogation to identify molecular effects of SLP in pre- and post-ischemic myocardium. Methodology/Principal Findings Male C57Bl/6 mice were implanted with 75 mg morphine or placebo pellets for 5 days. Resultant SLP did not modify cardiac function, and markedly reduced dysfunction and injury in perfused hearts subjected to 25 min ischemia/45 min reperfusion. Microarray analysis identified 14 up- and 86 down-regulated genes in normoxic hearts from SLP mice (?1.3-fold change, FDR?5%). Induced genes encoded sarcomeric/contractile proteins (Myh7, Mybpc3,Myom2,Des), natriuretic peptides (Nppa,Nppb) and stress-signaling elements (Csda,Ptgds). Highly repressed genes primarily encoded chemokines (Ccl2,Ccl4,Ccl7,Ccl9,Ccl13,Ccl3l3,Cxcl3), cytokines (Il1b,Il6,Tnf) and other proteins involved in inflammation/immunity (C3,Cd74,Cd83, Cd86,Hla-dbq1,Hla-drb1,Saa1,Selp,Serpina3), together with endoplasmic stress proteins (known: Dnajb1,Herpud1,Socs3; putative: Il6, Gadd45g,Rcan1) and transcriptional controllers (Egr2,Egr3, Fos,Hmox1,Nfkbid). Biological themes modified thus related to inflammation/immunity, together with cellular/cardiovascular movement and development. SLP also modified the transcriptional response to I-R (46 genes uniquely altered post-ischemia), which may influence later infarction/remodeling. This included up-regulated determinants of cellular resistance to oxidant (Mgst3,Gstm1,Gstm2) and other forms of stress (Xirp1,Ankrd1,Clu), and repression of stress-response genes (Hspa1a,Hspd1,Hsp90aa,Hsph1,Serpinh1) and Txnip. Conclusions Protection via SLP is associated with transcriptional repression of inflammation/immunity, up-regulation of sarcomeric elements and natriuretic peptides, and modulation of cell stress, growth and development, while conventional protective molecules are unaltered. PMID:23991079

Ashton, Kevin J.; Tupicoff, Amanda; Williams-Pritchard, Grant; Kiessling, Can J.; See Hoe, Louise E.; Headrick, John P.; Peart, Jason N.

2013-01-01

61

Apolipoprotein A-I Is a Potential Mediator of Remote Ischemic Preconditioning  

PubMed Central

Background Remote ischemic preconditioning (RIPC) has emerged as an attractive strategy in clinical settings. Despite convincing evidence of the critical role played by circulating humoral mediators, their actual identities remain unknown. In this study, we aimed to identify RIPC-induced humoral mediators using a proteomic approach. Methods and Results Rats were exposed to 10-min limb ischemia followed by 5- (RIPC 5?) or 10-min (RIPC 10?) reperfusion prior to blood sampling. The control group only underwent blood sampling. Plasma samples were analyzed using surface-enhanced laser desorption and ionization - time of flight - mass spectrometry (SELDI-TOF-MS). Three protein peaks were selected for their significant increase in RIPC 10?. They were identified and confirmed as apolipoprotein A-I (ApoA-I). Additional rats were exposed to myocardial ischemia-reperfusion (I/R) and assigned to one of the following groups RIPC+myocardial infarction (MI) (10-min limb ischemia followed by 10-min reperfusion initiated 20 minutes prior to myocardial I/R), ApoA-I+MI (10 mg/kg ApoA-I injection 10 minutes before myocardial I/R), and MI (no further intervention). In comparison with untreated MI rats, RIPC reduced infarct size (52.2±3.7% in RIPC+MI vs. 64.9±2.6% in MI; p<0.05). Similarly, ApoA-I injection decreased infarct size (50.9±3.8%; p<0.05 vs. MI). Conclusions RIPC was associated with a plasmatic increase in ApoA-I. Furthermore, ApoA-I injection before myocardial I/R recapitulated the cardioprotection offered by RIPC in rats. This data suggests that ApoA-I may be a protective blood-borne factor involved in the RIPC mechanism. PMID:24155931

Hibert, Pierre; Prunier-Mirebeau, Delphine; Beseme, Olivia; Chwastyniak, Maggy; Tamareille, Sophie; Lamon, Delphine; Furber, Alain; Pinet, Florence; Prunier, Fabrice

2013-01-01

62

Role of hypoxia inducible factor-1? in remote limb ischemic preconditioning.  

PubMed

Remote ischemic preconditioning (RIPC) has emerged as a feasible and attractive therapeutic procedure for heart protection against ischemia/reperfusion (I/R) injury. However, its molecular mechanisms remain poorly understood. Hypoxia inducible factor-1? (HIF-1?) is a transcription factor that plays a key role in the cellular adaptation to hypoxia and ischemia. This study's aim was to test whether RIPC-induced cardioprotection requires HIF-1? upregulation to be effective. In the first study, wild-type mice and mice heterozygous for HIF1a (gene encoding the HIF-1? protein) were subjected to RIPC immediately before myocardial infarction (MI). RIPC resulted in a robust HIF-1? activation in the limb and acute cardioprotection in wild-type mice. RIPC-induced cardioprotection was preserved in heterozygous mice, despite the low HIF-1? expression in their limbs. In the second study, the role of HIF-1? in RIPC was evaluated using cadmium (Cd), a pharmacological HIF-1? inhibitor. Rats were subjected to MI (MI group) or to RIPC immediately prior to MI (R-MI group). Cd was injected 18 0min before RIPC (Cd-R-MI group). RIPC induced robust HIF-1? activation in rat limbs and significantly reduced infarct size (IS). Despite Cd's inhibition of HIF-1? activation, RIPC-induced cardioprotection was preserved in the Cd-R-MI group. RIPC applied immediately prior to MI increased HIF-1? expression and attenuated IS in rats and wild-type mice. However, RIPC-induced cardioprotection was preserved in partially HIF1a-deficient mice and in rats pretreated with Cd. When considered together, these results suggest that HIF-1? upregulation is unnecessary in acute RIPC. PMID:24140799

Kalakech, Hussein; Tamareille, Sophie; Pons, Sandrine; Godin-Ribuot, Diane; Carmeliet, Peter; Furber, Alain; Martin, Valérie; Berdeaux, Alain; Ghaleh, Bijan; Prunier, Fabrice

2013-12-01

63

Plasma nitric oxide metabolite levels increase during successive exercise stress testing - A link to delayed ischemic preconditioning?  

PubMed Central

BACKGROUND: Animal studies have shown that nitric oxide is involved in delayed ischemic preconditioning. OBJECTIVES: To determine whether plasma nitrates and nitrites (NOx?, as measure of nitric oxide) are modified by two consecutive effort tests and whether these changes translate into clinical improvement METHODS: Twenty-two patients with ischemic heart disease each performed two effort tests at 24-h intervals. Plasma NOx? level was determined and compared before and after both stress tests. Peak effort, double product at peak effort and maximal ST segment depression were considered clinical endpoints and were compared between the two tests. RESULTS: Plasma NOx?increased slightly after the first exercise test compared with pretest value (17.05±1.6 ?mol/mL versus 15.38±1.4 ?mol/mL). In turn, after the second test there was a significant rise in NOx? level (23.65±2.2 ?mol/mL versus 15.10±1.3 ?mol/mL, P<0.03). The pretest values were almost identical between the two tests. Peak effort and double product at peak effort remained unchanged between the two tests. Although ischemic stress was the same, ST depression was significantly lower (P<0.01) for the second test (0.85±0.06 mm versus 1.73±0.16 mm). CONCLUSION: Our study shows an increased plasma NOx?level after the second of two consecutive exercise stress tests at 24-h intervals, along with a decrease of electrocardiographic consequences of approximately the same ischemic stress. These findings are consistent with experimental data in animals, which point to nitric oxide as a trigger and effector of ischemic preconditioning. PMID:19644584

Zdrenghea, Dumitru; Bodizs, Gyorgy; Ober, Mihai Claudiu; Ilea, Maria

2003-01-01

64

Ischemia preconditioning is neuroprotective in a rat cerebral ischemic injury model through autophagy activation and apoptosis inhibition.  

PubMed

Sublethal ischemic preconditioning (IPC) is a powerful inducer of ischemic brain tolerance. However, its underlying mechanisms are still not well understood. In this study, we chose four different IPC paradigms, namely 5 min (5 min duration), 5×5 min (5 min duration, 2 episodes, 15-min interval), 5×5×5 min (5 min duration, 3 episodes, 15-min intervals), and 15 min (15 min duration), and demonstrated that three episodes of 5 min IPC activated autophagy to the greatest extent 24 h after IPC, as evidenced by Beclin expression and LC3-I/II conversion. Autophagic activation was mediated by the tuberous sclerosis type 1 (TSC1)-mTor signal pathway as IPC increased TSC1 but decreased mTor phosphorylation. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and hematoxylin and eosin staining confirmed that IPC protected against cerebral ischemic/reperfusion (I/R) injury. Critically, 3-methyladenine, an inhibitor of autophagy, abolished the neuroprotection of IPC and, by contrast, rapamycin, an autophagy inducer, potentiated it. Cleaved caspase-3 expression, neurological scores, and infarct volume in different groups further confirmed the protection of IPC against I/R injury. Taken together, our data indicate that autophagy activation might underlie the protection of IPC against ischemic injury by inhibiting apoptosis. PMID:23903681

Xia, D Y; Li, W; Qian, H R; Yao, S; Liu, J G; Qi, X K

2013-07-01

65

Coronary microembolization does not induce acute preconditioning against infarction in pigs—the role of adenosine  

Microsoft Academic Search

Objective: After coronary microembolization (ME) adenosine is released from ischemic areas of the microembolized myocardium. This adenosine dilates vessels in adjacent nonembolized myocardium and increases coronary blood flow. For ischemic preconditioning (IP) to protect the myocardium against infarction, an increase in the interstitial adenosine concentration (iADO) prior to the subsequent ischemia\\/reperfusion is necessary. We hypothesized that the adenosine release after

Andreas Skyschally; Rainer Schulz; Petra Gres; Ina Konietzka; Claus Martin; Michael Haude; Raimund Erbel; Gerd Heusch

66

Release of a humoral circulating cardioprotective factor by remote ischemic preconditioning is dependent on preserved neural pathways in diabetic patients.  

PubMed

Efficacy of ischemic preconditioning is decreased in animal models of type 2 diabetes mellitus while the responses in humans with diabetes are contradictory. It is unknown whether attenuation is related to decreased release of a mediating humoral cardioprotective factor or reduced ability to respond in the target tissue. The aim of the present study was to investigate the release and effect of a circulating cardioprotective factor in type 2 diabetes mellitus patients. Blood samples were drawn from nine non-diabetic subjects, eight diabetic patients without peripheral neuropathy, and eight diabetic patients with peripheral neuropathy before (control) and after a remote ischemic preconditioning (rIPC) stimulus. Blood samples were dialyzed against Krebs-Henseleit buffer and the cardioprotective effects of the dialysates were tested in rabbit hearts mounted on a Langendorff model and subjected to 30-min global ischemia and 120-min reperfusion. rIPC dialysate from non-diabetic and diabetic subjects without peripheral neuropathy reduced infarct size and improved hemodynamic recovery compared to control dialysate from non-diabetic and diabetic subjects. However, in the subgroup of diabetic patients with neuropathy the cardioprotective effect was attenuated. These findings indicate that the release mechanism involves neural pathways. PMID:22821347

Jensen, Rebekka Vibjerg; Støttrup, Nicolaj Brejnholt; Kristiansen, Steen Buus; Bøtker, Hans Erik

2012-09-01

67

Ischemic Preconditioning Promotes Intrinsic Vascularization and Enhances Survival of Implanted Cells in an In Vivo Tissue Engineering Model  

PubMed Central

Ischemic preconditioning (IPC) is a potent and effective means of protecting cells against ischemic injury. The protection has been demonstrated to involve release of paracrine factors that promote cell survival and angiogenesis, factors important for successful tissue engineering. The aim of the present study was to determine whether IPC of a vascular bed in vivo is an effective strategy to prepare it for tissue engineering with implanted cells. To test this hypothesis, an in vivo vascularized tissue engineering approach was employed, whereby polyacrylic chambers were placed around the femoral vessels of adult Sprague-Dawley rats. IPC was induced by 3 cycles of 5?min femoral artery occlusion interspersed with 5-min periods of reperfusion. Rats subjected to IPC generated bigger tissue constructs at 7 and 28 days postimplantation of empty chambers (?50% increase in weight and volume, p<0.05). Morphometric counting of Masson trichrome stained tissue sections revealed significantly greater tissue construct volumes in ischemic preconditioned vascular beds at 7 and 28 days, increasing both fibrin matrix and vascularized tissue. Furthermore, morphometry of lectin-labeled blood vessels indicated an increase in vascular volume in IPC tissue constructs (?100% increase vs. control, p<0.05). To investigate the cytoprotective effect of IPC, we implanted DiI-labeled neonatal rat cardiomyocytes in the chambers for 3 days, and IPC significantly reduced apoptosis of implanted cells as determined by the TUNEL assay and cleaved caspase-3 immunostaining. Furthermore, IPC significantly increased the cardiac muscle volume and vascular volume at 28 days after implantation of cardiomyocytes. In conclusion, in vivo IPC promotes survival of implanted cardiomyocytes and is associated with enhanced angiogenesis. IPC may represent a new approach to optimize tissue engineering with implanted cells. PMID:22651554

Hsiao, Sarah T.; Lokmic, Zerina; Sivakumaran, Priyadharshini; Dusting, Gregory J.; Dilley, Rodney J.

2012-01-01

68

Ischemic preconditioning in the rat brain enhances the repair of endogenous oxidative DNA damage by activating the base-excision repair pathway  

Microsoft Academic Search

The development of ischemic tolerance in the brain, whereby a brief period of sublethal ‘preconditioning’ ischemia attenuates injury from subsequent severe ischemia, may involve the activation of multiple intracellular signaling events that promote neuronal survival. In this study, the potential role of inducible DNA base-excision repair (BER), an endogenous adaptive response that prevents the detrimental effect of oxidative DNA damage,

Wenjin Li; Yumin Luo; Feng Zhang; Armando P Signore; Glenn T Gobbel; Roger P Simon; Jun Chen

2006-01-01

69

Delta opioid receptor stimulation mimics ischemic preconditioning in human heart muscle  

Microsoft Academic Search

OBJECTIVESThe objective of this study was to examine whether the delta (?) opioid receptor isoform is expressed in the human heart and whether this receptor improves contractile function after hypoxic\\/reoxygenation injury.BACKGROUNDDelta opioid receptor agonists mimic preconditioning (PC) in rat myocardium, corresponding to known cardiac ? opioid receptor expression in this species.METHODSThe messenger RNA transcript encoding the ? opioid receptor was

Sam P Bell; Michael N Sack; Asha Patel; Lionel H Opie; Derek M Yellon

2000-01-01

70

Electro-acupuncture preconditioning abrogates the elevation of c-Fos and c-Jun expression in neonatal hypoxic-ischemic rat brains induced by glibenclamide, an ATP-sensitive potassium channel blocker  

Microsoft Academic Search

This study aimed to clarify the neuroprotective mechanism of electro-acupuncture (EA) preconditioning on hypoxic-ischemic brain injury (HIBI). Using Western blot, the expression of c-fos protein (c-Fos) and c-jun protein (c-Jun) induced by glibenclamide, an ATP-sensitive potassium (KATP) channel blocker was examined from cerebral cortical and hippocampal samples in neonatal hypoxic-ischemic rats, with or without EA preconditioning. EA was performed on

Ke-Wen Jiang; Zheng-Yan Zhao; Quan-Xiang Shui; Zhe-Zhi Xia

2004-01-01

71

Short-term ischemia usually used for ischemic preconditioning causes loss of dendritic integrity after long-term survival in the gerbil hippocampus  

Microsoft Academic Search

Ischemic preconditioning has been established as a powerful experimental neuroprotective strategy, both after global and focal cerebral ischemia. Little is known, however, about the structural and functional long-term outcome. Therefore, our present study was designed to check for potential subtle alterations in the hippocampus after long-term survival. Gerbils were subjected either to short-term ischemia of 2.5 min duration usually used for

Emre Tanay; Peter Mundel; Clemens Sommer

2006-01-01

72

Evidence that the acute phase of ischemic preconditioning does not require signaling by the A2B adenosine receptor  

PubMed Central

Ischemic preconditioning (IPC) is a protective phenomenon in which brief ischemia renders the myocardium resistant to subsequent ischemic insults. Here, we used A2BAR gene knock-out (A2BKO)/?-galactosidase reporter gene knock-in mice and the A2BAR antagonist ATL-801 to investigate the potential involvement of the A2BAR in IPC, focusing on the acute phase of protection. Cardioprotection provided by acute IPC elicited by two 3-min occlusion/3-min reperfusion cycles was readily apparent in an isolated, Langendorff-perfused mouse heart model in studies using hearts from A2BKO mice. IPC equivalently improved the recovery of contractile function following 20 min of global ischemia and 45 min of reperfusion in both WT and A2BKO hearts by ~30–40%, and equivalently decreased the release of cardiac tropinin I during the reperfusion period (from 5,969±925 to 1,595±674 ng/g and 4,376±739 to 2,278±462 ng/g using WT and A2BKO hearts, respectively). Similarly, the infarct size-reducing capacity of acute IPC in an in vivo model of infarction was fully manifest in experiments using A2BKO mice, as well as in experiments using rats pretreated with ATL-801. We did observe, however, a marked reduction in infarct size in rats following administration of the selective A2BAR agonist BAY 60-658 (~25% reduction at a dose of 1.0 mg/kg). While supportive of its concept as a cardioprotective receptor, these experiments indicate that the mechanism of the early phase of IPC is not dependent on signaling by the A2BAR. We present the idea that the A2BAR may contribute to the later stages of IPC dependent on the induction of stress-responsive genes. PMID:20797398

Maas, Jason E.; Wan, Tina C.; Figler, Robert A.; Gross, Garrett J.; Auchampach, John A.

2010-01-01

73

Hippocampal hypertrophy and sleep apnea: a role for the ischemic preconditioning?  

PubMed

The full impact of multisystem disease such as obstructive sleep apnoea (OSA) on regions of the central nervous system is debated, as the subsequent neurocognitive sequelae are unclear. Several preclinical studies suggest that its purported major culprits, intermittent hypoxia and sleep fragmentation, can differentially affect adult hippocampal neurogenesis. Although the prospective biphasic nature of chronic intermittent hypoxia in animal models of OSA has been acknowledged, so far the evidence for increased 'compensatory' neurogenesis in humans is uncertain. In a cross-sectional study of 32 patients with mixed severity OSA and 32 non-apnoeic matched controls inferential analysis showed bilateral enlargement of hippocampi in the OSA group. Conversely, a trend for smaller thalami in the OSA group was noted. Furthermore, aberrant connectivity between the hippocampus and the cerebellum in the OSA group was also suggested by the correlation analysis. The role for the ischemia/hypoxia preconditioning in the neuropathology of OSA is herein indicated, with possible further reaching clinical implications. PMID:24349453

Rosenzweig, Ivana; Kempton, Matthew J; Crum, William R; Glasser, Martin; Milosevic, Milan; Beniczky, Sandor; Corfield, Douglas R; Williams, Steven C; Morrell, Mary J

2013-01-01

74

Hippocampal Hypertrophy and Sleep Apnea: A Role for the Ischemic Preconditioning?  

PubMed Central

The full impact of multisystem disease such as obstructive sleep apnoea (OSA) on regions of the central nervous system is debated, as the subsequent neurocognitive sequelae are unclear. Several preclinical studies suggest that its purported major culprits, intermittent hypoxia and sleep fragmentation, can differentially affect adult hippocampal neurogenesis. Although the prospective biphasic nature of chronic intermittent hypoxia in animal models of OSA has been acknowledged, so far the evidence for increased ‘compensatory’ neurogenesis in humans is uncertain. In a cross-sectional study of 32 patients with mixed severity OSA and 32 non-apnoeic matched controls inferential analysis showed bilateral enlargement of hippocampi in the OSA group. Conversely, a trend for smaller thalami in the OSA group was noted. Furthermore, aberrant connectivity between the hippocampus and the cerebellum in the OSA group was also suggested by the correlation analysis. The role for the ischemia/hypoxia preconditioning in the neuropathology of OSA is herein indicated, with possible further reaching clinical implications. PMID:24349453

Rosenzweig, Ivana; Kempton, Matthew J.; Crum, William R.; Glasser, Martin; Milosevic, Milan; Beniczky, Sandor; Corfield, Douglas R.; Williams, Steven C.; Morrell, Mary J.

2013-01-01

75

Roles of Cx43-associated protein kinases in suppression of gap junction-mediated chemical coupling by ischemic preconditioning.  

PubMed

Ischemic preconditioning (PC) suppresses chemical coupling of cardiomyocytes via gap junctions (GJs) during ischemia, which is an adjunct mechanism of protection. The aim of this study was to characterize roles of protein kinases in PC-induced GJ modulation. In isolated rat hearts, ventricular tissues were sampled before and after ischemia with or without PC, and intercalated disc-rich fractions were separated for immunoprecipitation and immunoblotting. Levels of protein kinase C (PKC)-epsilon, p38mitogen-activated protein kinase (MAPK)-alpha, and Src coimmunoprecipitated with connexin-43 (Cx43) were increased after ischemia, whereas p38MAPKbeta was not detected in the Cx43 immunoprecipitates. PC did not modify the level of Cx43-Src complex after ischemia. However, PC enhanced Cx43-PKCepsilon complex formation, which was abolished by PKCepsilon translocation inhibitory peptide (TIP). In contrast, PC reduced Cx43-p38MAPKalpha complex level and p38MAPK activity in the Cx43 immunoprecipitates after ischemia. The effect of PC on Cx43-p38MAPKalpha interaction was mimicked by SB-203580, a p38MAPK inhibitor. PC reduced permeability of GJs to Lucifer yellow in the myocardium at 25 min after ischemia, and this effect was abolished by PKCepsilon-TIP. SB-203580 increased the GJ permeability at 15 min after ischemia compared with that in untreated controls, but the difference became insignificant 25 min after ischemia. In conclusion, PC has distinct effects on interaction of GJ Cx43 with PKCepsilon, p38MAPKalpha, and Src during ischemia. Suppression of GJ permeability during ischemia by PC is primarily achieved by enhanced interaction of Cx43 with PKCepsilon, which overwhelms the counterbalancing effect of reduced Cx43-p38MAPKalpha interaction. PMID:19098115

Naitoh, Kazuyuki; Yano, Toshiyuki; Miura, Tetsuji; Itoh, Takahito; Miki, Takayuki; Tanno, Masaya; Sato, Takahiro; Hotta, Hiroyuki; Terashima, Yoshiaki; Shimamoto, Kazuaki

2009-02-01

76

Effect of remote ischemic preconditioning on cognitive function after off-pump coronary artery bypass graft: a pilot study  

PubMed Central

Background Several studies have shown in animal models that remote ischemic preconditioning (rIPC) has a neuroprotective effect. However, a randomized controlled trial in human subjects to investigate the neuroprotective effect of rIPC after cardiac surgery has not yet been reported. Therefore, we performed this pilot study to determine whether rIPC reduced the occurrence of postoperative cognitive dysfunction in patients who underwent off-pump coronary artery bypass graft (OPCAB) surgery. Methods Seventy patients who underwent OPCAB surgery were assigned to either the control or the rIPC group using a computer-generated randomization table. The application of rIPC consisted of four cycles of 5 min ischemia and 5 min reperfusion on an upper limb using a blood pressure cuff inflating 200 mmHg before coronary artery anastomosis. The cognitive function tests were performed one day before surgery and again on postoperative day 7. We defined postoperative cognitive dysfunction as decreased postoperative test values more than 20% of the baseline values in more than two of the six cognitive function tests that were performed. Results In the cognitive function tests, there were no significant differences in the results obtained during the preoperative and postoperative periods for all tests and there were no mean differences observed in the preoperative and postoperative scores. The incidences of postoperative cognitive dysfunction in the control and rIPC groups were 28.6% (10 patients) and 31.4% (11 patients), respectively. Conclusions rIPC did not reduce the incidence of postoperative cognitive dysfunction after OPCAB surgery during the immediate postoperative period. PMID:24363844

Joung, Kyoung-Woon; Rhim, Jin-Ho; Chin, Ji-Hyun; Kim, Wook-Jong; Choi, Dae-Kee; Lee, Eun-Ho; Hahm, Kyung-Don; Sim, Ji-Yeon

2013-01-01

77

Hexokinase cellular trafficking in ischemia-reperfusion and ischemic preconditioning is altered in type I diabetic heart.  

PubMed

Diabetes mellitus (DM) has been reported to alter the cardiac response to ischemia-reperfusion (IR). In addition, cardioprotection induced by ischemic preconditioning (IPC) is often impaired in diabetes. We have previously shown that the subcellular localisation of the glycolytic enzyme hexokinase (HK) is causally related to IR injury and IPC protective potential. Especially the binding of HK to mitochondria and prevention of HK solubilisation (HK detachment from mitochondria) during ischemia confers cardioprotection. It is unknown whether diabetes affects HK localisation during IR and IPC as compared to non-diabetes. In this study we hypothesize that DM alters cellular trafficking of hexokinase in response to IR and IPC, possibly explaining the altered response to IR and IPC in diabetic heart. Control (CON) and type I diabetic (DM) rat hearts (65 mg/kg streptozotocin, 4 weeks) were isolated and perfused in Langendorff-mode and subjected to 35 min I and 30 min R with or without IPC (3 times 5 min I). Cytosolic and mitochondrial fractions were obtained at (1) baseline, i.e. after IPC but before I, (2) 35 min I, (3) 5 min R and (4) 30 min R. DM improved rate-pressure product recovery (RPP; 71 ± 10 % baseline (DM) versus 9 ± 1 % baseline (CON) and decreased contracture (end-diastolic pressure: 24 ± 8 mmHg (DM) vs 77 ± 4 mmHg (CON)) after IR as compared to control, and was associated with prevention of HK solubilisation at 35 min I. IPC improved cardiac function in CON but not in DM hearts. IPC in CON prevented HK solubilisation at 35 min I and at 5 min R, with a trend for increased mitochondrial HK. In contrast, the non-effective IPC in DM was associated with solubilisation of HK and decreased mitochondrial HK at early reperfusion and a reciprocal behaviour at late reperfusion. We conclude that type I DM significantly altered cellular HK translocation patterns in the heart in response to IR and IPC, possibly explaining altered response to IR and IPC in diabetes. PMID:23652994

Gurel, Ebru; Ustunova, Savas; Kapucu, Aysegul; Yilmazer, Nadim; Eerbeek, Otto; Nederlof, Rianne; Hollmann, Markus W; Demirci-Tansel, Cihan; Zuurbier, Coert J

2013-07-01

78

Protein SUMOylation is massively increased in hibernation torpor and is critical for the cytoprotection provided by ischemic preconditioning and hypothermia in SHSY5Y cells  

PubMed Central

Hibernation torpor provides an excellent natural model of tolerance to profound reductions in blood flow to the brain and other organs. Here, we report that during torpor of 13-lined ground squirrels, massive SUMOylation occurs in the brain, liver, and kidney. The level of small ubiquitin-related modifier (SUMO) conjugation coincides with the expression level of Ubc9, the SUMO specific E2-conjugating enzyme. Hypothermia alone also increased SUMO conjugation, but not as markedly as hibernation torpor. Increased SUMO conjugation (induced by Ubc9 overexpression, ischemic preconditioning (PC)±hypothermia) was necessary and sufficient for tolerance of SHSY5Y neuroblastoma cells to oxygen/glucose deprivation (OGD) (‘in vitro ischemia’); decreased SUMO conjugation (induced by a dominant-negative Ubc9) severely reduced tolerance to OGD in these cells. These data indicate that post-translational modification of proteins by SUMOylation is a prominent feature of hibernation torpor and is critical for cytoprotection by ischemic PC± hypothermia in SHSY5Y cells subjected to OGD. PMID:16955077

Lee, Yang-ja; Miyake, Shin-ichi; Wakita, Hideaki; McMullen, David C; Azuma, Yoshiaki; Auh, Sungyoung; Hallenbeck, John M

2008-01-01

79

Transient Limb Ischemia Alters Serum Protein Expression in Healthy Volunteers: Complement C3 and Vitronectin May Be Involved in Organ Protection Induced by Remote Ischemic Preconditioning  

PubMed Central

The protective mechanism underlying remote ischemic preconditioning (RIPC) is unclear. This study aims to verify whether the protein expression profile in the serum could be altered by RIPC and to detect potential protein mediators. Transient limb ischemia consisting of three cycles of 5-min ischemia followed by 5-min reperfusion was performed on sixty healthy volunteers. Serum samples were collected at 30?min before transient limb ischemia and at 1 hour (h), 3?h, 8?h, 24?h, and 48?h after completion of three cycles. Changes in the serum protein profile were analyzed by two-dimensional gel electrophoresis and proteins were identified by MALDI-TOF/TOF mass spectrometry. Fourteen differentially expressed proteins were identified and, respectively, involved in immune system, lipid binding and metabolism, apoptosis, and blood coagulation. Complement C3, vitronectin, and apolipoprotein A-I were further confirmed by western blotting, and the results showed that their contents decreased significantly after transient limb ischemia. It is concluded that transient limb ischemia alters the serum protein expression profile in human being, and that reduction of serum contents of complement C3 and vitronectin may represent an important part of the mechanism whereby RIPC confers its protection. PMID:24363825

Pang, Ting; Zhang, Nan-Rong; Jin, San-Qing; Pan, San-Qiang

2013-01-01

80

Deletion of the Innate Immune NLRP3 Receptor Abolishes Cardiac Ischemic Preconditioning and Is Associated with Decreased Il-6/STAT3 Signaling  

PubMed Central

Objective Recent studies indicate that the innate immune system is not only triggered by exogenous pathogens and pollutants, but also by endogenous danger signals released during ischemia and necrosis. As triggers for the innate immune NLRP3 inflammasome protein complex appear to overlap with those for cardiac ischemia-reperfusion (I/R) and ischemic preconditioning (IPC), we explored the possibility that the NLRP3 inflammasome is involved in IPC and acute I/R injury of the heart. Principal Findings Baseline cardiac performance and acute I/R injury were investigated in isolated, Langendorff-perfused hearts from wild-type (WT), ASC?/? and NLRP3?/? mice. Deletion of NLRP3 inflammasome components ASC?/? or NLRP3?/? did not affect baseline performance. The deletions exacerbated I/R-induced mechanical dysfunction, but were without effect on I/R-induced cell death. When subjected to IPC, WT and ASC?/? hearts were protected against I/R injury (improved function and less cell death). However, IPC did not protect NLRP3?/? hearts against I/R injury. NLRP3?/? hearts had significantly decreased cardiac IL-6 levels with a trend towards lower IL-1? levels at end reperfusion, suggesting abrogation of IPC through diminished IL-6 and/or IL-1? signaling. Subsequent experiments showed that neutralising IL-6 using an antibody against IL-6 abrogated IPC in WT hearts. However, inhibition of the IL-1r receptor with the IL-1 receptor inhibitor Anakinra (100 mg/L) did not abrogate IPC in WT hearts. Analysis of survival kinases after IPC demonstrated decreased STAT3 expression in NLRP3?/? hearts when compared to WT hearts. Conclusions The data suggest that the innate immune NLRP3 protein, in an NLRP3-inflammasome-independent fashion, is an integral component of IPC in the isolated heart, possibly through an IL-6/STAT3 dependent mechanism. PMID:22848390

Eerbeek, Otto; Koeman, Anneke; Pulskens, Wilco P.; Butter, Loes M.; Leemans, Jaklien C.; Hollmann, Markus W.

2012-01-01

81

Activities of cardiac tissue matrix metalloproteinases 2 and 9 are reduced by remote ischemic preconditioning in cardiosurgical patients with cardiopulmonary bypass  

PubMed Central

Background Transient episodes of ischemia in a remote organ or tissue (remote ischemic preconditioning, RIPC) can attenuate myocardial injury. Myocardial damage is associated with tissue remodeling and the matrix metalloproteinases 2 and 9 (MMP-2/9) are crucially involved in these events. Here we investigated the effects of RIPC on the activities of heart tissue MMP-2/9 and their correlation with serum concentrations of cardiac troponin T (cTnT), a marker for myocardial damage. Methods In cardiosurgical patients with cardiopulmonary bypass (CPB) RIPC was induced by four 5 minute cycles of upper limb ischemia/reperfusion. Cardiac tissue was obtained before as well as after CPB and serum cTnT concentrations were measured. Tissue derived from control patients (N?=?17) with high cTnT concentrations (?0.32 ng/ml) and RIPC patients (N?=?18) with low cTnT (?0.32 ng/ml) was subjected to gelatin zymography to quantify MMP-2/9 activities. Results In cardiac biopsies obtained before CPB, activities of MMP-2/9 were attenuated in the RIPC group (MMP-2: Control, 1.13?±?0.13 a.u.; RIPC, 0.71?±?0.12 a.u.; P??0.05). In cardiac biopsies taken after CPB activities of pro- and active MMP-2/9 were not different between the groups (P?>?0.05). Spearman’s rank tests showed that MMP-2/9 activities in cardiac tissue obtained before CPB were positively correlated with postoperative cTnT serum levels (MMP-2, P?=?0.016; MMP-9, P?=?0.015). Conclusions Activities of MMP-2/9 in cardiac tissue obtained before CPB are attenuated by RIPC and are positively correlated with serum concentrations of cTnT. MMPs may represent potential targets for RIPC mediated cardioprotection. Trial registration ClinicalTrials.gov identifier NCT00877305. PMID:24712447

2014-01-01

82

Myocardial preconditioning: a model or a phenomenon?  

PubMed

A brief ischemic episode (ischemic preconditioning) limits myocardial necrosis produced by a prolonged period of coronary artery occlusion and reperfusion. In absence of infarction, lack of cumulative ATP depletion, and ventricular arrhythmias and dysfunction "stunning" in models of intermittent ischemia and reperfusion also could be a component of an adaptive response to brief ischemia (preconditioning). Nonischemic stimuli also precondition the myocardium against ventricular arrhythmias and infarction by activating endogenous mechanism(s) of protection similar to that induced by ischemic preconditioning. Preservation of myocardial ATP, abolishing purine release, attenuation of free radical production, activation of adenosine receptors and KATP channels, and induction of heat shock proteins are common responses to ischemic and nonischemic stimuli of preconditioning. Although a significant reduction in myocardial infarction is critical to myocardial salvage and patient survival, it is equally important to have a functioning heart that can sustain systemic pressure without inotropic support or assist devices. It is scientifically challenging and clinically important to elucidate the mechanisms of myocardial preconditioning. However, it is necessary to expand the definition of myocardial preconditioning to include nonischemic stimuli of preconditioning and other important monitors of myocardial protection such as ventricular function and electrophysiological stability in addition to that of infarction. PMID:7579831

Abd-Elfattah, A S; Wechsler, A S

1995-07-01

83

Vector-Free and Transgene-Free Human iPS Cells Differentiate into Functional Neurons and Enhance Functional Recovery after Ischemic Stroke in Mice  

PubMed Central

Stroke is a leading cause of human death and disability in the adult population in the United States and around the world. While stroke treatment is limited, stem cell transplantation has emerged as a promising regenerative therapy to replace or repair damaged tissues and enhance functional recovery after stroke. Recently, the creation of induced pluripotent stem (iPS) cells through reprogramming of somatic cells has revolutionized cell therapy by providing an unlimited source of autologous cells for transplantation. In addition, the creation of vector-free and transgene-free human iPS (hiPS) cells provides a new generation of stem cells with a reduced risk of tumor formation that was associated with the random integration of viral vectors seen with previous techniques. However, the potential use of these cells in the treatment of ischemic stroke has not been explored. In the present investigation, we examined the neuronal differentiation of vector-free and transgene-free hiPS cells and the transplantation of hiPS cell-derived neural progenitor cells (hiPS-NPCs) in an ischemic stroke model in mice. Vector-free hiPS cells were maintained in feeder-free and serum-free conditions and differentiated into functional neurons in vitro using a newly developed differentiation protocol. Twenty eight days after transplantation in stroke mice, hiPS-NPCs showed mature neuronal markers in vivo. No tumor formation was seen up to 12 months after transplantation. Transplantation of hiPS-NPCs restored neurovascular coupling, increased trophic support and promoted behavioral recovery after stroke. These data suggest that using vector-free and transgene-free hiPS cells in stem cell therapy are safe and efficacious in enhancing recovery after focal ischemic stroke in mice. PMID:23717557

Mohamad, Osama; Faulkner, Ben; Chen, Dongdong; Yu, Shan Ping; Wei, Ling

2013-01-01

84

Signal pathway involved in the development of hypoxic preconditioning in rat hepatocytes  

Microsoft Academic Search

Ischemic preconditioning improves liver resistance to hypoxia and reduces reperfusion injury following transplantation. However, the intracellular signals that mediate the development of liver hypoxic preconditioning are largely unknown. We have investigated the signal pathway leading to preconditioning in freshly isolated rat hepatocytes. Hepatocytes were preconditioned by 10-minute incubation under hypoxic conditions followed by 10 minutes of reoxygenation and subsequently exposed

Rita Carini; Maria Grazia De Cesaris; Roberta Splendore; Daria Vay; Cinzia Domenicotti; Maria Paola Nitti; Dimitri Paola; Maria Adelaide Pronzato; Emanuele Albano

2001-01-01

85

Preconditioning Balloons  

NSDL National Science Digital Library

Students use balloons (a polymer) to explore preconditioningâa viscoelastic material behavior that is important to understand when designing biomedical devices. They improve their understanding of preconditioning by measuring the force needed to stretch a balloon to the same displacement multiple times. Students gain experience in data collection and graph interpretation.

Integrated Teaching And Learning Program

86

Preconditioning the Human Brain: Practical Considerations for Proving Cerebral Protection  

Microsoft Academic Search

Ischemic preconditioning has evolved as one of the most powerful strategies for cerebral protection in laboratory models of\\u000a ischemia. Translating the success of laboratory studies to human cerebral protection will necessitate an approximation of\\u000a laboratory conditions. This would require a practical, easily implemented method of preconditioning and clinical settings\\u000a in which cerebral ischemia is anticipated, thereby allowing cerebral preconditioning prior

Sebastian Koch

2010-01-01

87

Oxidant Preconditioning Protects Human Proximal Tubular Cells against Lethal Oxidant Injury via p38 MAPK and Heme Oxygenase1  

Microsoft Academic Search

Ischemic preconditioning protects the kidney from subsequent ischemic injury but the signal transduction pathways involved are unknown. Human proximal tubular (HK-2) cells were protected from injury with 2.5 mM H2O2 by preconditioning with a single 15-min exposure to 500 ?M H2O2 followed by 16 h of recovery (oxidant preconditioning). To identify the signaling pathways involved in oxidant preconditioning, we utilized

H. Thomas Lee; Hua Xu; Ayuko Ota-Setlik; Charles W. Emala

2003-01-01

88

Delayed remote ischemic preconditioning produces an additive cardioprotection to sevoflurane postconditioning through an enhanced heme oxygenase 1 level partly via nuclear factor erythroid 2-related factor 2 nuclear translocation.  

PubMed

Although both sevoflurane postconditioning (SPoC) and delayed remote ischemic preconditioning (DRIPC) have been proved effective in various animal and human studies, the combined effect of these 2 strategies remains unclear. Therefore, this study was designed to investigate this effect and elucidate the related signal mechanisms in a Langendorff perfused rat heart model. After 30-minute balanced perfusion, isolated hearts were subjected to 30-minute ischemia followed by 60-minute reperfusion except 90-minute perfusion for control. A synergic cardioprotective effect of SPoC (3% v/v) and DRIPC (4 cycles 5-minute occlusion/5-minute reflow at the unilateral hindlimb once per day for 3 days before heart isolation) was observed with facilitated cardiac functional recovery and decreased cardiac enzyme release. The infarct size-limiting effect was more pronounced in the combined group (6.76% ± 2.18%) than in the SPoC group (16.50% ± 4.55%, P < .001) or in the DRIPC group (10.22% ± 2.57%, P = .047). Subsequent analysis revealed that an enhanced heme oxygenase 1 (HO-1) expression, but not protein kinase B/AKt or extracellular signal-regulated kinase 1 and 2 activation, was involved in the synergic cardioprotective effect, which was further confirmed in the messenger RNA level of HO-1. Such trend was also observed in the nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation, an upstream regulation of HO-1. In addition, correlation analysis showed a significantly positive relationship between HO-1 expression and Nrf2 translocation (r = 0.729, P < .001). Hence, we conclude that DRIPC may produce an additive cardioprotection to SPoC through an enhanced HO-1 expression partly via Nrf2 translocation. PMID:24651515

Zhou, Chenghui; Li, Huatong; Yao, Yuntai; Li, Lihuan

2014-11-01

89

Lipopolysaccharide preconditioning attenuates neuroapoptosis and improves functional recovery through activation of Nrf2 in traumatic spinal cord injury rats.  

PubMed

The previous studies suggested that low-dose lipopolysaccharide (LPS) provides neuroprotection against subsequent challenge with ischemic/reperfusion injury in the brain. But there were few reports about the neuroprotective effects of low-dose LPS against spinal cord injury (SCI). In this study, we evaluated the effect of low-dose LPS preconditioning on neuroapoptosis status after traumatic SCI (TSCI), using a standardized contusion model (NYU, New York University, impactor). SCI-induced rats were randomly divided into three groups: sham operation, control (receiving only normal saline) and LPS preconditioning (0.2 mg/kg, ip; 72 hours before injury). Neurologic function was assessed by the Basso, Beattie and Bresnahan (BBB) score at 6, 12, 24, 48 and 72 hours after TSCI. Rats were sacrificed at 72 hours postinjury. Histological changes were studied using Nissl staining. Apoptotic neural cells were assessed using the TdT-mediated dUTP Nick End Labeling (TUNEL) assay. Nuclear factor erythroid 2-related factor 2 (Nrf2) and caspase-3 were detected with immunohistochemistry and Western blot. LPS preconditioning reduced neuron apoptosis, improved neurologic outcome and actived Nrf2 expression. Moreover, Histological changes and the number of apoptotic cells were correlated with Nrf2 expression after the rats suffered the SCI. Our results suggest that LPS preconditioning exerted a neuroprotective effect against TSCI in rats, and activation of Nrf2 was believed to be one of the contributing mechanisms. PMID:23215850

Li, Wei-Chao; Jiang, Dian-Ming; Hu, Ning; Qi, Xiao-Tong; Qiao, Bo; Luo, Xiao-Ji

2013-04-01

90

Mitochondrial Preconditioning: A Potential Neuroprotective Strategy  

PubMed Central

Mitochondria have long been known as the powerhouse of the cell. However, these organelles are also pivotal players in neuronal cell death. Mitochondrial dysfunction is a prominent feature of chronic brain disorders, including Alzheimer's disease (AD) and Parkinson's disease (PD), and cerebral ischemic stroke. Data derived from morphologic, biochemical, and molecular genetic studies indicate that mitochondria constitute a convergence point for neurodegeneration. Conversely, mitochondria have also been implicated in the neuroprotective signaling processes of preconditioning. Despite the precise molecular mechanisms underlying preconditioning-induced brain tolerance are still unclear, mitochondrial reactive oxygen species generation and mitochondrial ATP-sensitive potassium channels activation have been shown to be involved in the preconditioning phenomenon. This review intends to discuss how mitochondrial malfunction contributes to the onset and progression of cerebral ischemic stroke and AD and PD, two major neurodegenerative disorders. The role of mitochondrial mechanisms involved in the preconditioning-mediated neuroprotective events will be also discussed. Mitochondrial targeted preconditioning may represent a promising therapeutic weapon to fight neurodegeneration. PMID:20838473

Correia, Sónia C.; Carvalho, Cristina; Cardoso, Susana; Santos, Renato X.; Santos, Maria S.; Oliveira, Catarina R.; Perry, George; Zhu, Xiongwei; Smith, Mark A.; Moreira, Paula I.

2010-01-01

91

Ventilation Air Preconditioning Systems  

E-print Network

dedicated to preconditioning the outside air. This paper discusses two such systems for cooling and dehumidification applications: one with a separate preconditioning unit and one with separate ventilation and return air paths in a single unit. Both deep...

Khattar, M.; Brandemuehl, M. J.

1996-01-01

92

Intracellular Free Calcium and Mitochondrial Membrane Potential in Ischemia\\/Reperfusion and Preconditioning  

Microsoft Academic Search

Moderation of calcium perturbations has been implicated in ischemic preconditioning. As mitochondria possess an effective Ca2+transporting system driven by the mitochondrial membrane potential, experiments were performed to study time-averaged intracellular free calcium and the mitochondrial membrane potential during preconditioning and ischemia–reperfusion. Isolated rat hearts were subjected to 5 min of preconditioning, a 9-min intervening reperfusion and 21 min of ischemia

Kari V Ylitalo; Antti Ala-Rämi; Erkki V Liimatta; Keijo J Peuhkurinen; Ilmo E Hassinen

2000-01-01

93

Sarcolemmal Versus Mitochondrial ATP-Sensitive K1 Channels and Myocardial Preconditioning  

Microsoft Academic Search

Ischemic preconditioning (IPC) is a phenomenon in which single or multiple brief periods of ischemia have been shown to protect the heart against a more prolonged ischemic insult, the result of which is a marked reduction in myocardial infarct size, severity of stunning, or incidence of cardiac arrhythmias. Although a number of substances and signaling pathways have been proposed to

Garrett J. Gross; Ryan M. Fryer

2010-01-01

94

Hypoxically preconditioned human peripheral blood mononuclear cells improve blood flow in hindlimb ischemia xenograft model  

PubMed Central

Transplantation of peripheral blood mononuclear cells (PBMNCs) is a promising therapeutic approach for the treatment of hindlimb ischemia. However, insufficient angiogenesis in ischemic hindlimb after cell transplantation reduces the importance and practicality of this approach. Previously, we demonstrated using mouse models that hypoxic preconditioning augmented the cellular functions of rodent PBMNCs, such as increased cell adhesion capacity and accelerated neovascularization in ischemic hindlimb. To test the clinical application of this therapeutic strategy in this study, we investigated whether the protocol of hypoxic preconditioning, which was established in a condition of 2% O2 for 24 h, can be made available for human PBMNCs (hPBMNCs). In addition, we grafted preconditioned hPBMNCs in a hindlimb ischemia mouse model. Hypoxic preconditioning enhanced cell adhesion capacity and oxidative stress resistance in hPBMNCs. We also observed an up-regulation of platelet endothelial cell adhesion molecule-1 (PECAM-1) in hPBMNCs by hypoxic preconditioning. Furthermore, preconditioned hPBMNCs significantly recovered limb blood flow in ischemic mice after transplantation. These results indicate that our established preconditioning protocol is available for hPBMNCs to effectively reinforce multiple cellular functions. Taken together with our series of study, we believe that this simple but powerful therapeutic strategy will be helpful in curing patients with severe hindlimb ischemia.

Kudo, Tomoaki; Kubo, Masayuki; Katsura, Shunsaku; Nishimoto, Arata; Ueno, Koji; Samura, Makoto; Fujii, Yasuhiko; Hosoyama, Tohru; Hamano, Kimikazu

2014-01-01

95

Silymarin and its constituents in cardiac preconditioning.  

PubMed

Silymarin, a standardised extract of Silybum marianum (milk thistle), comprises mainly of silybin, with dehydrosilybin (DHSB), quercetin, taxifolin, silychristin and a number of other compounds which are known to possess a range of salutary effects. Indeed, there is evidence for their role in reducing tumour growth, preventing liver toxicity, and protecting a number of organs against ischemic damage. The hepatoprotective effects of silymarin, especially in preventing Amanita and alcohol intoxication induced damage to the liver, are a well established fact. Likewise, there is weighty evidence that silymarin possesses antimicrobial and anticancer activities. Additionally, it has emerged that in animal models, silymarin can protect the heart, brain, liver and kidneys against ischemia reperfusion injury, probably by preconditioning. The mechanisms of preconditioning are, in general, well studied, especially in the heart. On the other hand, the mechanism by which silymarin protects the heart from ischemia remains largely unexplored. This review, therefore, focuses on evaluating existing studies on silymarin induced cardioprotection in the context of the established mechanisms of preconditioning. PMID:24879900

Zholobenko, A; Modriansky, M

2014-09-01

96

Glutamate preconditioning prevents neuronal death induced by combined oxygen-glucose deprivation in cultured cortical neurons.  

PubMed

The study of ischemic tolerance is critical in the development of strategies for the treatment of ischemic stroke. We used the oxygen and glucose deprivation (OGD) paradigm in cultured cortical neurons as an in vitro approach to elucidate the mechanism of protection conferred by glutamate preconditioning. Pretreatment of neurons with N-methyl-d-aspartate (NMDA) receptor antagonists prevented OGD-induced cell death whereas alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor and voltage-dependent Ca(++) channel (VDCC) blockers were without effect. Neurons preconditioned with glutamate exhibited resistant to damage induced by OGD. The ischemic tolerance depended on the duration of preconditioning exposure and the interval between preconditioning exposure and test challenge. Protective efficacy was blocked by the NMDA or AMPA receptor antagonists but not by the VDCC blocker. Furthermore, neuroprotective effect was not seen if extracellular Ca(++) was omitted or removed with EGTA. Pretreatment with staurosporin and 2-[N-(2-hydroxyethyl)]-N-(4-methoxybenzenesulfonyl)] amino-N-(4-chlorocinnamyl)-N-methylbenzylamine (KN93) but not 2-(4-Morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one (LY294002) or 1,4-diamino-2,3-dicyano-1, 4-bis[2-aminophenylthio] butadiene (U0126) significantly reduced ischemic tolerance. Preconditioning increased phosphorylated levels of cAMP responsive element binding protein (CREB) and pretreatment with CRE-decoy oligonucleotide completely blocked preconditioning-induced increase in cell viability. Importantly, glutamate preconditioning increased Bcl-2 expression that was blocked by KN93, staurosporin and CRE-decoy oligonucleotide. These results suggest that preconditioning with glutamate conferred neuroprotection against subsequent OGD by inducing p-CREB-mediated Bcl-2 expression. PMID:18589412

Lin, Chia-Ho; Chen, Po-See; Gean, Po-Wu

2008-07-28

97

Epsilon protein kinase C as a potential therapeutic target for the ischemic heart  

Microsoft Academic Search

Abstract Ischemic heart disease is the leading cause of morbidity and mortality in the western world. Ischemic damage,can occur by acute myocardial infarction, stable angina, cardiac stunning, and myocardial hibernation. In addition, Fscheduled_ ischemic events, occurring during cardiac surgery, heart transplantation, and elective angioplasty, can also result in cardiac damage. Ischemic or pharmacological preconditioning,can,decrease,the extent of damage,to the myocardium.,Although,the mechanism,of

Koichi Inagaki; Eric Churchill; Daria Mochly-Rosen

2006-01-01

98

Glutamate preconditioning prevents neuronal death induced by combined oxygen–glucose deprivation in cultured cortical neurons  

Microsoft Academic Search

The study of ischemic tolerance is critical in the development of strategies for the treatment of ischemic stroke. We used the oxygen and glucose deprivation (OGD) paradigm in cultured cortical neurons as an in vitro approach to elucidate the mechanism of protection conferred by glutamate preconditioning. Pretreatment of neurons with N-methyl-d-aspartate (NMDA) receptor antagonists prevented OGD-induced cell death whereas ?-amino-3-hydroxy-5-methyl-4-isoxazole

Chia-Ho Lin; Po-See Chen; Po-Wu Gean

2008-01-01

99

Preconditioning Methods for Multidimensional Aerodynamics  

E-print Network

Preconditioning Methods for Multidimensional Aerodynamics E. Turkel School of Mathematical Sciences of Design Aerodynamics Braunschweig, Germany 1 #12; Contents 1 Introduction 5 1.1 General requirements

Turkel, Eli

100

Protein Kinase C- ? is Responsible for the Protection of Preconditioning in Rabbit Cardiomyocytes  

Microsoft Academic Search

The role of protein kinase C (PKC) in the protection of ischemic preconditioning (PC) is still controversial, partly because of the multiple isozymes of PKC and the inability to directly measure PKC activity in vivo. In this study we have used novel peptide inhibitors which correspond to part of the amino acid sequence from the isozyme-specific RACK-binding site on the

Guang S. Liu; Michael V. Cohen; Daria Mochly-Rosen; James M. Downey

1999-01-01

101

Bihemispheric ischemic tolerance induced by a unilateral focal cortical lesion.  

PubMed

The purpose of the present study was to determine whether a unilateral photothrombotic brain lesion induces bilateral ischemic tolerance towards a subsequent severe ischemia performed 5 days later. Severe ischemia was induced by transient (1h; t) or permanent (p) occlusion of the middle cerebral artery (MCAO). Rats were sacrificed 24h later. Preconditioning reduced the size of subsequent infarcts in both hemispheres. This effect was most prominent with tMCAO, and ipsilateral preconditioning was more effective than contralateral preconditioning (% of hemispheric volume, mean ± SD: 31.9 ± 3.7 to 19.0 ± 10.3 with ipsilateral tMCAO; 31.9 ± 3.7 to 22.9 ± 4.9 with contralateral tMCAO; 64.7 ± 4.3% to 47.2 ± 12.5% with ipsilateral pMCAO; 64.7 ± 4.3% to 53.1 ± 8.9% with contralateral pMCAO). Ischemic preconditioning was associated with a successive bilateral up-regulation of superoxide dismutases which may be involved in the development of ischemic tolerance. Our data suggest that a focal ischemic brain lesion induces neuroprotective mechanisms in extensive brain areas and thus cause bilateral ischemic tolerance within a certain time window. PMID:24835408

Schumacher, Lena; Urbach, Anja; Lutzenburg, Michael; Bidmon, Hans-J; Witte, Otto W

2014-06-27

102

Translocation of PKC, protein phosphatase inhibition and preconditioning of rabbit cardiomyocytes.  

PubMed

This study was designed to test the hypothesis that induction of the preconditioned state results in a sustained translocation of protein kinase C (PKC) which accounts for the memory associated with preconditioning. Isolated rabbit cardiomyocytes were subjected to established preconditioning protocols using either adenosine or transient ischemia. At timed intervals during induction of preconditioning (PC), post-incubation or final sustained ischemia, cells were harvested, subjected to digitonin lysis and separated into cytosolic and particulate fractions. Samples were evaluated by Western blot analysis with monoclonal antibodies to alpha, epsilon, zeta and gamma PKC isozymes, and bands were qualified by densitometry. Internal controls for each experiment included oxygenated cardiomyocytes and cell with PKC translocation evoked by treatment with phorbol 12-myristate 13-acetate (PMA). For control oxygenated cells, the particulate fraction contained about 30% of PKC epsilon, 5-10% of PKC alpha and 60-70% of PKC zeta. Preconditioning with adenosine (100 microM) or 10 min ischemia had no significant effect on these percentages. Furthermore, the relative amounts of PKC isozymes associated with the particulate fraction of control and preconditioned cells did not differ after a postincubation in oxygenated buffer or during a final ischemic incubation. PMA and ingenol completely translocated the epsilon and alpha isoforms, while thymeleatoxin totally translocated PKC alpha but only partially (50%) translocated PKC epsilon. The distribution of PKC zeta between fractions was not affected by any drug. The protein phosphatase inhibitor calyculin A protected cells mimicking preconditioning. This protection was blocked by preincubation with the selective PKC inhibitor calphostin C but was largely retained if calphostin C was added only during the final ischemic period. It is concluded that PKC activity is required for preconditioning, but a sustained translocation of PKC above basal levels is not necessary for protection of rabbit cardiomyocytes in vitro. PMID:8841935

Armstrong, S C; Hoover, D B; Delacey, M H; Ganote, C E

1996-07-01

103

Microglia in ischemic brain injury  

PubMed Central

Microglia are resident CNS immune cells that are active sensors in healthy brain and versatile effectors under pathological conditions. Cerebral ischemia induces a robust neuroinflammatory response that includes marked changes in the gene-expression profile and phenotype of a variety of endogenous CNS cell types (astrocytes, neurons and microglia), as well as an influx of leukocytic cells (neutrophils, macrophages and T-cells) from the periphery. Many molecules and conditions can trigger a transformation of surveying microglia to microglia of an alerted or reactive state. Here we review recent developments in the literature that relate to microglial activation in the experimental setting of in vitro and in vivo ischemia. We also present new data from our own laboratory demonstrating the direct effects of in vitro ischemic conditions on the microglial phenotype and genomic profile. In particular, we focus on the role of specific molecular signaling systems, such as hypoxia inducible factor-1 and Toll-like receptor-4, in regulating the microglial response in this setting. We then review histological and novel radiological data that confirm a key role for microglial activation in the setting of ischemic stroke in humans. We also discuss recent progress in the pharmacologic and molecular targeting of microglia in acute ischemic stroke. Finally, we explore how recent studies on ischemic preconditioning have increased interest in pre-emptively targeting microglial activation in order to reduce stroke severity. PMID:20401171

Weinstein, Jonathan R; Koerner, Ines P; Moller, Thomas

2010-01-01

104

Ischemic injury of the developing heart  

PubMed Central

Cardiac tolerance to ischemia changes significantly during ontogenetic development: the immature heart appears to be more resistant to ischemic injury than the adult myocardium. The mechanisms of the higher tolerance of the developing heart have not yet been satisfactorily clarified; age-dependent changes in energy metabolism have to be taken into consideration. Marked ontogenetic changes are displayed by the mitochondrial membrane potential (MMP): in newborn rats a single population of mitochondria with a relatively high MMP was observed but, with increasing age, the second population with a lower MMP appeared. Adaptation to chronic hypoxia and ischemic preconditioning failed to improve ischemic tolerance of the rat heart on the first postnatal day; the cardioprotective effect only developed at the end of the first postnatal week. Decreasing tolerance of the neonatal heart to ischemia is thus counteracted by the development of endogenous protection. It seems likely that both mitochondrial KATP channels and nitric oxide may be involved in the protective mechanisms of adaptation to chronic hypoxia but not to that of ischemic preconditioning, at least in neonatal rats. Basic knowledge of the possible improvements of immature heart tolerance to ischemia may contribute to the design of therapeutic strategies for both pediatric cardiology and cardiac surgery. PMID:19649230

Ost'adal, Bohuslav; Ost'adalova, Ivana; Skarka, L; Kolar, F; Kopecky, Jan

2002-01-01

105

Short-term hypoxic preconditioning improved survival following cardiac arrest and resuscitation in rats.  

PubMed

Cardiac arrest and resuscitation produces delayed mortality and hippocampal neuronal death in rats. Hypoxic preconditioning has been to shown to protect the brain from ischemic insults. We have previously reported that with chronic hypobaric hypoxia, the accumulation of hypoxic-inducible factor-1 alpha (HIF-1?) and its target genes was increased for the first several days of hypoxic exposure, and returned to baseline level by 3 weeks when angiogenesis is completed. In this study, we investigated the effect of short-term (3 days) and long-term (21 days) hypoxic preconditioning on recovery from cardiac arrest and resuscitation in rats. Our data showed that the overall survival rate was considerably improved in the short-term hypoxic preconditioning group compared to the non-preconditioned controls (86 %, 6/7 vs. 54 %, 7/13); however, the survival rate in the long-term hypoxic preconditioning group was decreased. Our data suggest that hypoxic preconditioning provides protection after cardiac arrest and resuscitation more likely through increased accumulation of HIF-1? and its target genes rather than through successful vascular adaptation as a result of hypoxia-induced angiogenesis. PMID:24729248

Xu, Kui; Lamanna, Joseph C

2014-01-01

106

Induction of ischemic tolerance as a promising treatment against diabetic retinopathy  

PubMed Central

Diabetic retinopathy is a leading cause of acquired blindness, and it is the most common ischemic disorder of the retina. Available treatments are not very effective. Efforts to inhibit diabetic retinopathy have focused either on highly specific therapeutic approaches for pharmacologic targets or using genetic approaches to change expression of certain enzymes. However, it might be wise to choose innovative treatment modalities that act by multiple potential mechanisms. The resistance to ischemic injury, or ischemic tolerance, can be transiently induced by prior exposure to a non-injurious preconditioning stimulus. A complete functional and histologic protection against retinal ischemic damage can be achieved by previous preconditioning with non-damaging ischemia. In this review, we will discuss evidence that supports that ischemic conditioning could help avert the dreaded consequences that results from retinal diabetic damage. PMID:25368643

Rosenstein, Ruth E.; Fernandez, Diego C.

2014-01-01

107

Induction of ischemic tolerance as a promising treatment against diabetic retinopathy.  

PubMed

Diabetic retinopathy is a leading cause of acquired blindness, and it is the most common ischemic disorder of the retina. Available treatments are not very effective. Efforts to inhibit diabetic retinopathy have focused either on highly specific therapeutic approaches for pharmacologic targets or using genetic approaches to change expression of certain enzymes. However, it might be wise to choose innovative treatment modalities that act by multiple potential mechanisms. The resistance to ischemic injury, or ischemic tolerance, can be transiently induced by prior exposure to a non-injurious preconditioning stimulus. A complete functional and histologic protection against retinal ischemic damage can be achieved by previous preconditioning with non-damaging ischemia. In this review, we will discuss evidence that supports that ischemic conditioning could help avert the dreaded consequences that results from retinal diabetic damage. PMID:25368643

Rosenstein, Ruth E; Fernandez, Diego C

2014-09-01

108

Ischemic colitis  

Microsoft Academic Search

BackgroundIschemic colitis almost always occurs in older patients. Because life expectancy is increasing, more and more often physicians will face this problem. The aim of this study was to identify factors leading to surgery in the acute phase of the disease, and to evaluate mortality and long-term follow-up evaluation.

Michel Huguier; Alain Barrier; Pierre Y. Boelle; Sydney Houry; Francois Lacaine

2006-01-01

109

Hyperthermic preconditioning prevents blood–brain barrier disruption produced by hypoxia–ischemia in newborn rat  

Microsoft Academic Search

Effect of hyperthermic preconditioning on disruption of blood–brain barrier induced by hypoxic–ischemic insult was examined. Seven-day-old Wistar rats were separated into (1) pre-heated (15 min of hyperthermia at 41.5–42.0°C) or (2) non-heated group (33°C). Twenty-four hours after conditioning, all rats were subjected to 2 h hypoxia–ischemia (8% oxygen\\/92% nitrogen, at 33°C), then 24 h later all brains were examined for

Tomoaki Ikeda; Xiao Y Xia; Yi X Xia; Tsuyomu Ikenoue

1999-01-01

110

PVM and IP multicast  

SciTech Connect

This report describes a 1994 demonstration implementation of PVM that uses IP multicast. PVM`s one-to-many unicast implementation of its pvm{_}mcast() function is replaced with reliable IP multicast. Performance of PVM using IP multicast over local and wide-area networks is measured and compared with the original unicast implementation. Current limitations of IP multicast are noted.

Dunigan, T.H.; Hall, K.A.

1996-12-01

111

LPS-Induced Delayed Preconditioning Is Mediated by Hsp90 and Involves the Heat Shock Response in Mouse Kidney  

PubMed Central

Introduction We and others demonstrated previously that preconditioning with endotoxin (LPS) protected from a subsequent lethal LPS challenge or from renal ischemia-reperfusion injury (IRI). LPS is effective in evoking the heat shock response, an ancient and essential cellular defense mechanism, which plays a role in resistance to, and recovery from diseases. Here, by using the pharmacological Hsp90 inhibitor novobiocin (NB), we investigated the role of Hsp90 and the heat shock response in LPS-induced delayed renal preconditioning. Methods Male C57BL/6 mice were treated with preconditioning (P: 2 mg/kg, ip.) and subsequent lethal (L: 10 mg/kg, ip.) doses of LPS alone or in combination with NB (100 mg/kg, ip.). Controls received saline (C) or NB. Results Preconditioning LPS conferred protection from a subsequent lethal LPS treatment. Importantly, the protective effect of LPS preconditioning was completely abolished by a concomitant treatment with NB. LPS induced a marked heat shock protein increase as demonstrated by Western blots of Hsp70 and Hsp90. NB alone also stimulated Hsp70 and Hsp90 mRNA but not protein expression. However, Hsp70 and Hsp90 protein induction in LPS-treated mice was abolished by a concomitant NB treatment, demonstrating a NB-induced impairment of the heat shock response to LPS preconditioning. Conclusion LPS-induced heat shock protein induction and tolerance to a subsequent lethal LPS treatment was prevented by the Hsp90 inhibitor, novobiocin. Our findings demonstrate a critical role of Hsp90 in LPS signaling, and a potential involvement of the heat shock response in LPS-induced preconditioning. PMID:24646925

Kaucsár, Tamás; Bodor, Csaba; Godó, Mária; Szalay, Csaba; Révész, Csaba; Németh, Zalán; Mózes, Miklós; Szénási, Gábor; Rosivall, László; S?ti, Csaba; Hamar, Péter

2014-01-01

112

IP switching—ATM under IP  

Microsoft Academic Search

IP traffic on the Internet and private enterprise networks has been growing exponentially for some time. This growth is beginning to stress the traditional, processor based design of current day routers. Switching technology offers much higher aggregate bandwidth but presently only offers a layer-2 bridging solution. Various proposals are under way to support IP routing over an ATM network. However,

Peter Newman; Greg Minshall; Thomas L. Lyon

1998-01-01

113

Collateral recruitment and “warm-up” after first exercise in ischemic heart disease  

Microsoft Academic Search

Background Proposed mechanisms for “warm-up” after angina on first exercise include ischemic preconditioning and collateral recruitment. The aim of this study was to determine whether patients with ischemic heart disease and well-developed coronary collateral vessels have a greater warm-up response than those with no visible collateral vessels. Methods And Results Fifteen patients with a total coronary occlusion and collateral vessels

I. Patrick Kay; John Kittelson; Ralph A. H. Stewart

2000-01-01

114

Income Protection (IP) Insurance  

E-print Network

Income Protection (IP) Insurance Kenneth Stokes, G.A. ?Art? Barnaby, Mark Waller and Joe Outlaw* The Income Protection (IP) program insures the producer against lost income from reductions in yield or price. This policy pays when the harvested...Income Protection (IP) Insurance Kenneth Stokes, G.A. ?Art? Barnaby, Mark Waller and Joe Outlaw* The Income Protection (IP) program insures the producer against lost income from reductions in yield or price. This policy pays when the harvested...

Stokes, Kenneth; Barnaby, G. A. Art; Waller, Mark L.; Outlaw, Joe

1999-06-09

115

Secure Mobile IP Communication  

E-print Network

of Mobile IP & IPSec - 2 - #12;Integration of Mobile IP & IPSec - 3 - Table of contents: 1 ABSTRACT 5 2 Threats 13 3.2.2 Security Issues In Mobile IP 14 3.3 Security models 14 4 IPSEC OVERVIEW 16 4.1 Where does IPSec fit in? 16 4.2 Securing the IP layer 16 4.3 Security services offered by IPSec 17 4.3.1 Spoofing

Braun, Torsten

116

Effects of diabetes on myocardial infarct size and cardioprotection by preconditioning and postconditioning  

PubMed Central

In spite of the current optimal therapy, the mortality of patients with ischemic heart disease (IHD) remains high, particularly in cases with diabetes mellitus (DM) as a co-morbidity. Myocardial infarct size is a major determinant of prognosis in IHD patients, and development of a novel strategy to limit infarction is of great clinical importance. Ischemic preconditioning (PC), postconditioning (PostC) and their mimetic agents have been shown to reduce infarct size in experiments using healthy animals. However, a variety of pharmacological agents have failed to demonstrate infarct size limitation in clinical trials. One of the possible reasons for the discrepancy between the results of animal experiments and clinical trials is that co-morbidities, including DM, modified myocardial responses to ischemia/reperfusion and to cardioprotective agents. Here we summarize observations of the effects of DM on myocardial infarct size and ischemic PC and PostC and discuss perspectives for protection of DM hearts. PMID:22694800

2012-01-01

117

Preconditioning to mild oxidative stress mediates astroglial neuroprotection in an IL-10-dependent manner.  

PubMed

Oxidative stress plays an important role in the pathogenesis of various brain insults, including stroke. Astroglia are the main glial cells that play a fundamental role in maintaining the homeostasis of the CNS. They are important for protection from injury and aid the brain in functional recovery after injuries. It has been shown that the brain can be prepared to withstand an oxidative stress insult by a process known as preconditioning. We used primary astroglial cell culture to investigate whether preconditioning to mild oxidative stress and glucose deprivation (OSGD) can increase both astroglia survival and neuroprotective features. We found that preconditioning astroglia to mild OSGD increases astroglial survival of a second insult through activation of the NF-E2-related factor-2 (Nrf-2) pathway. Moreover, we found that Nrf-2 is highly expressed in adult brain astroglia and that preconditioning to OSGD in vivo, such as in a murine model of ischemic stroke, leads to a significant increase in astroglial Nrf-2 expression. Furthermore, we discovered an increase in neuroprotection, as measured by increased neuronal cell survival, following OSGD in the presence of medium from astroglia exposed to a mild OSGD condition. Interestingly, we discovered a significant increase in astroglial secretion of the anti-inflammatory cytokine IL-10 vs. the pro-inflammatory cytokine IL-1? in mild vs. severe oxidative stress, respectively. We demonstrated that preconditioning astroglia to mild oxidative stress increases neuroprotection in an IL-10-dependent manner. By using tert-butylhydroquinone (tBHQ), a known specific activator of Nrf-2, we found that Nrf-2 can enhance IL-10 expression. Further studies of Nrf-2-mediated cellular pathways in astroglia through IL-10 may provide useful insights into the development of therapeutic interventions following oxidative stress insults such as ischemic stroke. PMID:23313057

Segev-Amzaleg, Niva; Trudler, Dorit; Frenkel, Dan

2013-05-01

118

Differential role of mGlu1 and mGlu5 receptors in rat hippocampal slice models of ischemic tolerance.  

PubMed

Activation of glutamate receptors has been proposed as a key factor in the induction of ischemic tolerance. We used organotypic rat hippocampal slices exposed to 30 min oxygen-glucose deprivation (OGD) to evaluate postischemic pyramidal cell death in the CA1 subregion. In this model, 10 min exposure to OGD 24 h before the exposure to toxic OGD was not lethal and reduced the subsequent OGD neurotoxicity by approximately 53% (ischemic preconditioning). Similarly, a 30 min exposure to the group I mGlu receptor agonist DHPG (10 microM) significantly reduced OGD neurotoxicity 24 h later (pharmacological preconditioning). Ischemic tolerance did not develop when either the selective mGlu1 antagonists LY367385 and 3-MATIDA or the AMPA/KA antagonist CNQX were present in the incubation medium during exposure to sublethal OGD. Neither the NMDA antagonist MK801 nor the mGlu5 antagonist MPEP affected the preconditioning process. On the other hand, pharmacological preconditioning was prevented not only by LY367385 or CNQX, but also by MPEP. In preconditioned slices, the toxic responses to AMPA or NMDA were reduced. The neurotoxicty of 100 microM DHPG in slices simultaneously exposed to a mild (20 min) OGD was differentially altered in the two preconditioning paradigms. After ischemic preconditioning, DHPG neurotoxicity was reduced in a manner that was sensitive to LY367385 but not to MPEP, whereas after pharmacological preconditioning it was enhanced in a manner that was sensitive to MPEP but not to LY367385. Our results show that mGlu1 and mGlu5 receptors are differentially involved in the induction and expression of ischemic tolerance following two diverse preconditioning stimuli. PMID:17610579

Werner, Claudia G; Scartabelli, Tania; Pancani, Tristano; Landucci, Elisa; Moroni, Flavio; Pellegrini-Giampietro, Domenico E

2007-06-01

119

Expression of signal transduction genes differs following hypoxic or isoflurane preconditioning of rat hippocampal slice cultures  

PubMed Central

Background Preconditioning neurons with non-injurious hypoxia (hypoxic preconditioning, HPC) or the anesthetic isoflurane (APC) induces tolerance of severe ischemic stress. The mechanisms of both types of preconditioning in the hippocampus require moderate increases in intracellular Ca2+ and activation of protein kinase signaling. We hypothesized that the expression of signal transduction genes would be similar following APC and HPC. Methods Hippocampal slice cultures prepared from 9 day-old rats were preconditioned with hypoxia (5 min 95% nitrogen/5% carbon dioxide) or 1% isoflurane in air/5% carbon dioxide for 1 hr. A day later cultures were subjected to 10 min oxygen and glucose deprivation (simulated ischemia). Intracellular Ca2+, measured in CA1 neurons at the completion of preconditioning, and cell death in CA1, CA3 and dentate regions was assessed 48 hr after simulated ischemia. Message RNA encoding 119 signal transduction genes was quantified with rat complimentary DNA micro arrays from pre oxygen-glucose deprivation samples. Results Both APC and HPC increased intracellular Ca2+ approximately 50 nM and decreased CA1, CA3 and dentate neuron death by about 50% following simulated ischemia. Many signaling genes were increased after preconditioning, with hypoxia increasing more apoptosis/survival genes (8 of 10) than isoflurane (0 of 10). In contrast, isoflurane increased more cell cycle/development/growth genes than did hypoxia (8 of 14 genes, versus 1 of 14). Conclusions Despite sharing similar upstream signaling and neuroprotective outcomes, the genomic response to APC and HPC is different. Increased expression of anti-apoptosis genes following HPC and cell development genes following APC has implications both for neuroprotection and long-term effects of anesthetics. PMID:19568165

Bickler, Philip E.; Fahlman, Christian S.

2012-01-01

120

Voice over IP Calculator  

NSDL National Science Digital Library

The Voice over IP Calculator Web site actually consists of four free online tools that can be used to estimate bandwidth requirements and voice paths for a planned VoIP system. The four tools are: Lines and IP Bandwidth Calculator, Erlangs and Bandwidth Calculator, Minutes and Lines Calculator, and Erlangs and Lines Calculator. Each utility is very easy to use, but is mainly intended for experienced IT workers.

2008-02-12

121

Strategies to promote donor cell survival: combining preconditioning approach with stem cell transplantation  

PubMed Central

Stem cell transplantation has emerged as a potential modality in cardiovascular therapeutics due to their inherent characteristics of self-renewal, unlimited capacity for proliferation and ability to cross lineage restrictions and adopt different phenotypes. Constrained by extensive death in the unfriendly milieu of ischemic myocardium, the results of heart cell therapy in experimental animal models as well as clinical studies have been less than optimal. Several factors which play a role in early cell death after engraftment in the ischemic myocardium include; absence of survival factors in the transplanted heart, disruption of cell-cell interaction coupled with loss of survival signals from matrix attachments, insufficient vascular supply and elaboration of inflammatory cytokines resulting from ischemia and/or cell death. This article reviews various signaling pathways involved in triggering highly complex forms of cell death and provides critical appreciation of different novel anti-death strategies developed from the knowledge gained from using an ischemic preconditioning approach. The use of pharmacological preconditioning for up-regulation of pro-survival proteins and cardiogenic markers in the transplanted stem cells will be discussed. PMID:18561945

Haider, Husnain Kh; Ashraf, Muhammad

2008-01-01

122

Investigating the role of the actin regulating complex ARP2/3 in rapid ischemic tolerance induced neuro-protection  

PubMed Central

Neuronal morphology is highly sensitive to ischemia, although some re-organization may promote neuroprotection. In this study we investigate the role of actin regulating proteins (ARP2, ARP3 and WAVE-1) and their role in rapid ischemic tolerance. Using an established in vitro model of rapid ischemic tolerance, we show that WAVE-1 protein levels are stabilized following brief tolerance inducing ischemia (preconditioning). The stabilization appears to be due to a reduction in the ubiquitination of WAVE-1. Levels of ARP2, ARP3 and N-WASP were not affected by ischemic preconditioning. Immunocytochemical studies show a relocalization of ARP2 and ARP3 proteins in neurons following preconditioning ischemia, as well as a re-organization of actin. Blocking the protein kinase CK2 using emodin blocks ischemic tolerance, and our data suggests CK2 binds to WAVE-1 in neurons. We observe an increase in binding of the ARP2 subunit with WAVE-1. The neuroprotection observed following preconditioning is inhibited when cells are transduced with an N-WASP CA domain that blocks the activation of ARP2/3. Together these data show that ischemia affects actin regulating enzymes, and that the ARP2/3 pathway plays a role in rapid ischemic tolerance induced neuroprotection. PMID:24379906

Jessick, Veronica J; Xie, Mian; Pearson, Andrea N; Torrey, Dan J; Ashley, Michelle D; Thompson, Simon; Meller, Robert

2013-01-01

123

The Protective Effects of Ischemic Postconditioning against Stroke: From Rapid to Delayed and Remote Postconditioning  

PubMed Central

The author reviews the protective effects of ischemic postconditioning, a recently emerging strategy with broad implications in the search for new treatments in stroke and myocardial ischemic injury. Ischemic postconditioning, which refers to a series of brief ischemia and reperfusion cycles applied immediately at the site of the ischemic organ after reperfusion, results in reduced infarction in both cerebral and myocardial ischemia. Conventional postconditioning induced within a few minutes after reperfusion is arbitrarily defined as rapid postconditioning. In contrast, postconditioning performed hours to days after stroke is defined as delayed postconditioning. In addition, postconditioning can be mimicked using anesthetics or other pharmacological agents as stimuli to protect against ischemia/reperfusion injury or performed in a distant organ, which is known as remote postconditioning. In this article, the author discusses the conceptual origin of classical rapid ischemic postconditioning and its evolution into a term that represents a broad range of stimuli or triggers, including delayed postconditioning, pharmacological postconditioning, and remote postconditioning. Thereafter, various in vivo and in vitro models of postconditioning and its potential protective mechanisms are discussed. Since the concept of postconditioning is so closely associated with that of preconditioning and both share some common protective mechanisms, whether a combination of preconditioning and postconditioning offers greater protection than preconditioning or postconditioning alone is also discussed. PMID:22053169

Zhao, Heng

2011-01-01

124

TIA (Transient Ischemic Attack)  

MedlinePLUS

TIA (Transient Ischemic Attack) Updated:Oct 2,2014 Excerpted from “ Why Rush? ”, Stroke Connection January/February 2009 (Science update October 2012) While transient ischemic attack (TIA) is often labeled “mini-stroke,” ...

125

IP Virtual Private Networks  

Microsoft Academic Search

Existing technologies, including frame relay and ATM, can be used to create virtual private networks (VPNs) over a shared infrastructure. However, two new technologies, tag switching and IP security, may be used to create IP VPNs that are independent of the access network and the core technology. This paper examines these technologies, compares them to each other and to existing

S Hills; D McGlaughlin; N Hanafi

2000-01-01

126

Mild activation of poly(ADP-ribose) polymerase (PARP) is neuroprotective in rat hippocampal slice models of ischemic tolerance.  

PubMed

Ischemic tolerance is a phenomenon in which exposure to a mild preconditioning stress results in resistance to a subsequent lethal ischemic insult. Here we investigated the role of poly(ADP-ribose) polymerase (PARP) in the development of ischemic tolerance by using organotypic rat hippocampal slices exposed to 30 min oxygen-glucose deprivation (OGD), which leads to selective injury of the CA1 subregion 24 h later. We developed models of pharmacological preconditioning by exposing slices to subtoxic concentrations of either N-methyl-D-aspartate (NMDA) or (S)-3,5-dihydroxyphenylglycine (DHPG) and then, 24 h later, to 30 min OGD. Under these conditions, we observed a significant reduction in OGD-induced CA1 damage. Exposure of slices to the PARP-1 and -2 inhibitors TIQ-A, PJ-34 and UPF 1069 during preconditioning prevented the development of OGD tolerance in a concentration-dependent manner. NMDA and DHPG preconditioning increased the activity of PARP, as detected by immunoblots using antibodies against the poly(ADP-ribose) polymer product, but was not associated with consumption of cellular NAD(+) or ATP. Neuroprotection induced by preconditioning was also prevented by the caspase inhibitor Z-VAD-FMK. The modest but significant increase in caspase-3/7 induced by preconditioning, however, was not associated with PARP-1 cleavage, as occurred with staurosporine. Finally, TIQ-A prevented the activation of ERK1/2 and Akt induced by NMDA preconditioning, suggesting that the protective mechanism evoked by PARP requires activation of these prosurvival mediators. Our results suggest that preconditioning with appropriate pharmacological stimuli may promote neuroprotective mechanisms triggered by the sublethal activation of two otherwise deleterious executioners such as PARP and caspase-3/7. PMID:22639866

Gerace, Elisabetta; Scartabelli, Tania; Formentini, Laura; Landucci, Elisa; Moroni, Flavio; Chiarugi, Alberto; Pellegrini-Giampietro, Domenico E

2012-07-01

127

Preconditioning the Helmholtz Equation for Rigid Ducts.  

National Technical Information Service (NTIS)

An innovative hyperbolic preconditioning technique is developed for the numerical solution of the Helmholtz equation which governs acoustic propagation in ducts. Two pseudo-time parameters are used to produce an explicit iterative finite difference scheme...

K. J. Baumeister, K. L. Kreider

1998-01-01

128

Preconditioning techniques for stochastic partial differential equations  

E-print Network

This thesis is about preconditioning techniques for time dependent stochastic Partial Differential Equations arising in the broader context of Uncertainty Quantification. State-of-the-art methods for an efficient integration ...

Spantini, Alessio

2013-01-01

129

Semidefinite Programming Based Preconditioning for More Robust ...  

E-print Network

Grant from the Natural Science and Engineering Research Council (Canada). 1 ... In practice, the input separable matrix is perturbed with some noise and it is ..... It is rather straightforward to analyze the influence of a preconditioning on SPA.

2013-10-08

130

Fetal brain genomic reprogramming following asphyctic preconditioning  

PubMed Central

Background Fetal asphyctic (FA) preconditioning is effective in attenuating brain damage incurred by a subsequent perinatal asphyctic insult. Unraveling mechanisms of this endogenous neuroprotection, activated by FA preconditioning, is an important step towards new clinical strategies for asphyctic neonates. Genomic reprogramming is thought to be, at least in part, responsible for the protective effect of preconditioning. Therefore we investigated whole genome differential gene expression in the preconditioned rat brain. FA preconditioning was induced on embryonic day 17 by reversibly clamping uterine circulation. Male control and FA offspring were sacrificed 96 h after FA preconditioning. Whole genome transcription was investigated with Affymetrix Gene1.0ST chip. Results Data were analyzed with the Bioconductor Limma package, which showed 53 down-regulated and 35 up-regulated transcripts in the FA-group. We validated these findings with RT-qPCR for adh1, edn1, leptin, rdh2, and smad6. Moreover, we investigated differences in gene expression across different brain regions. In addition, we performed Gene Set Enrichment Analysis (GSEA) which revealed 19 significantly down-regulated gene sets, mainly involved in neurotransmission and ion transport. 10 Gene sets were significantly up-regulated, these are mainly involved in nucleosomal structure and transcription, including genes such as mecp2. Conclusions Here we identify for the first time differential gene expression after asphyctic preconditioning in fetal brain tissue, with the majority of differentially expressed transcripts being down-regulated. The observed down-regulation of cellular processes such as neurotransmission and ion transport could represent a restriction in energy turnover which could prevent energy failure and subsequent neuronal damage in an asphyctic event. Up-regulated transcripts seem to exert their function mainly within the cell nucleus, and subsequent Gene Set Enrichment Analysis suggests that epigenetic mechanisms play an important role in preconditioning induced neuroprotection. PMID:23800330

2013-01-01

131

IPS User's Guide  

Microsoft Academic Search

IntroductionIPS[2] is an interactive, trace driven performance measurement system for parallel and distributedprograms. It runs on DECstation, Sun, Vax, Sequent Symmetry, and Cray Y-MP computers(or a heterogeneous combination of these computers). IPS provides a large amount of performancedata about the execution of a parallel program, and this information is organized hierarchicallyso that access to it is easy and intuitive.Performance data

Barton P. Miller; Bruce Irvin; Hi Low; Jeff Hollingsworth

1989-01-01

132

Lipopolysaccharide preconditioning attenuates apoptotic processes and improves neuropathologic changes after spinal cord injury in rats.  

PubMed

We have shown earlier that administration of low-dose lipopolysaccharide (LPS) significantly contributed to recovery of motor function after traumatic spinal cord injury in the adult female rat. Using the same standardized animal model, we have now designed a set of experiments to test the hypothesis that LPS preconditioning attenuates stress-related apoptotic processes early after spinal cord trauma. The lower thoracic spinal cord injury in adult female Sprague-Dawley rats was caused by a 10 g weight rod drop from 25 mm on the dural surface of the exposed spinal cord at T10. The rats were randomly assigned to three groups: Sham injury, control (received normal saline alone), and LPS preconditioning (0.2 mg/kg, ip; 72 h prior to the injury). The animals were euthanized at 72 h postinjury. Neuropathologic changes were assessed using hematoxylin and eosin staining. SCI-induced apoptosis were observed by transmission electron microscopy. Caspase-3, cleaved caspase-3, Bax, and Bcl-2 were examined with immunohistochemistry or Western blotting. Compared with the control group, LPS preconditioning group showed significant improvement in the SCI-induced morphology changes. Furthermore, LPS preconditioning reduced the expressions of apoptotic markers caspase-3, cleaved caspase-3, and Bax, upregulated the expression of antiapoptotic marker Bcl-2 in the samples of spinal cord. Low-dose LPS attenuated the recruitment of inflammatory cells and the proliferation of glial cells in the site of injury. LPS preconditioning has neuroprotective effects against TSCI in rats due to its antiapoptosis properties as shown by the inhibition of caspase pathway and the upregulation of antiapoptotic protein. PMID:24205811

Li, Wei-Chao; Jiang, Rong; Jiang, Dian-Ming; Zhu, Feng-Chen; Su, Bao; Qiao, Bo; Qi, Xiao-Tong

2014-08-01

133

IP switching and gigabit routers  

Microsoft Academic Search

To cope with the growth in the Internet and corporate IP networks, we require IP routers capable of much higher performance than is possible with existing architectures. This article examines two approaches to the design of a high-performance router, the gigabit router and the IP switch, and then provides some detail on the implementation of an IP switch and the

P. Newman; G. Minshall; T. Lyon; L. Huston

1997-01-01

134

Ischemic postconditioning: from receptor to end-effector.  

PubMed

Ischemic preconditioning, a robust cardioprotective intervention, has limited clinical efficacy because it must be initiated before myocardial ischemia. Conversely, ischemic postconditioning, repeated brief reocclusions of a coronary artery after release of prolonged coronary occlusion, provides cardioprotection in clinically feasible settings, that is, coronary angioplasty. Ischemic postconditioning's signaling is being investigated to identify pharmacological triggers that could be used without angioplasty. In initial minutes of reperfusion H(+) washes out of previously ischemic cells. pH rises enabling mitochondrial permeability transition pores (MPTPs) to form leading to cessation of ATP production and cell necrosis. Coronary reocclusions maintain sufficient acidosis to keep MPTP closed while signaling is initiated that can generate endogenous antagonists of MPTP formation even after cellular pH normalizes. Reintroduction of oxygen generates reactive oxygen species that activate protein kinase C to increase sensitivity of adenosine A(2b) receptors allowing adenosine released from ischemic cells to bind leading to activation of phosphatidylinositol 3-kinase and extracellular signal-regulated kinase 1/2. Phosphatidylinositol 3-kinase activation results in phosphorylation of Akt promoting activation of nitric oxide synthase and nitric oxide production, which inhibits glycogen synthase kinase-3?, perhaps the final cytosolic signaling step before inhibition of MPTP formation. Interference with MPTP may be the final step that determines cell salvage. PMID:20518705

Cohen, Michael V; Downey, James M

2011-03-01

135

Ischemic optic neuropathy.  

PubMed

Ischemic optic neuropathy is the most frequent cause of vision loss in middle age. Clinical and laboratory research studies have begun to clarify the natural history, clinical presentation, diagnostic criteria and pathogenesis of various ischemic nerve injuries. As a result, physicians are acquiring new tools to aid in the diagnosis and potential treatment of ischemic nerve injury. The aim of this review is to examine recent data on anterior and posterior ischemic optic neuropathy and to provide a framework for physicians to manage and counsel affected individuals. PMID:18826805

Athappilly, Geetha; Pelak, Victoria S; Mandava, Naresh; Bennett, Jeffrey L

2008-10-01

136

Xenon preconditioning: molecular mechanisms and biological effects  

PubMed Central

Xenon is one of noble gases and has been recognized as an anesthetic for more than 50?years. Xenon possesses many of the characteristics of an ideal anesthetic, but it is not widely applied in clinical practice mainly because of its high cost. In recent years, numerous studies have demonstrated that xenon as an anesthetic can exert neuroprotective and cardioprotective effects in different models. Moreover, xenon has been applied in the preconditioning, and the neuroprotective and cardioprotective effects of xenon preconditioning have been investigated in a lot of studies in which some mechanisms related to these protections are proposed. In this review, we summarized these mechanisms and the biological effects of xenon preconditioning. PMID:23305274

2013-01-01

137

Ionizing radiation as preconditioning against transient cerebral ischemia in rats.  

PubMed

Induction of ischemic tolerance (IT), the ability of an organism to survive an otherwise lethal ischemia, is the most effective known approach to preventing postischemic damage. IT can be induced by exposing animals to a broad range of stimuli. In this study we tried to induce IT of brain neurons using ionizing radiation (IR). A preconditioning (pre-C) dose of 10, 20, 30 or 50 Gy of gamma rays was used 2 days before an 8 min ischemia in adult male rats. Ischemia alone caused the degeneration of almost one half of neurons in CA1 region of hippocampus. However, a significant decrease of the number of degenerating neurons was observed after higher doses of radiation (30 and 50 Gy). Moreover, ischemia significantly impaired the spatial memory of rats as tested in Morris's water maze. In rats with a 50 Gy pre-C dose, the latency times were reduced to values close to the control level. Our study is the first to reveal that IR applied in sufficient doses can induce IT and thus allow pyramidal CA1 neurons to survive ischemia. In addition, we show that the beneficial effect of IR pre-C is proportional to the radiation dose. PMID:25032511

Kokošová, Natália; Danielisová, Viera; Smajda, Be?adik; Burda, Jozef

2014-10-01

138

Support graph preconditioning for elliptic finite element problems  

E-print Network

A relatively new preconditioning technique called support graph preconditioning has many merits over the traditional incomplete factorization based methods. A major limitation of this technique is that it is applicable to symmetric diagonally...

Wang, Meiqiu

2009-05-15

139

Treating acute ischemic stroke  

Microsoft Academic Search

Acute ischemic stroke (AIS) is a common disorder that has only one associated approved therapy: intravenous tissue plasminogen activator (iv t-PA). A limiting factor to the use of iv t-PA is that it must be initiated within 3 h of stroke onset. Efforts to expand the therapeutic time window are underway and include image evaluation of the ischemic penumbra to

Marc Fisher; Birgül Bastan

2008-01-01

140

Pharmacologically induced preconditioning with diazoxide: a novel approach to brain protection 3 1 The Thoracic Surgery Directors Association (TSDA) Resident Research Award, sponsored by Medtronic, Inc, was established in 1990 to encourage resident research in cardiothoracic surgery. Abstracts submitted to The Society of Thoracic Surgeons (STS) Program Committee representing research performed by residents were forwarded to the TSDA to be considered for this award. The abstracts were reviewed by the TSDA Executive Committee, consisting of Gordon N. Olinger, President, Edward D. Verrier, President-Elect, Jeffrey P. Gold, Secretary\\/Treasurer, and Richard Shemin, Councillor-at-Large. 3 2 The eleventh TSDA Resident Research Award was given to Jay G. Shake, MD, a general surgery resident, in the Department of Surgery, Johns Hopkins Hospital, Baltimore, MD. He received a monetary award of $2,500 and an engraved desktop award. 3 3 The TSDA, with support by Medtronic, Inc, makes this award ann  

Microsoft Academic Search

Background. Ischemic preconditioning is an endogenous mechanism whereby brief periods of ischemia render neurons resistant to subsequent lethal insults. This protection appears to alter cellular apoptosis and can be induced by potassium channel openers acting on the inner membrane of the mitochondria (mitoKATP). To test the hypothesis that pharmacologic preconditioning could provide neuroprotection, the mitoKATP opener diazoxide was used in

Jay G Shake; Eric A Peck; Eduardo Marban; Vincent L Gott; Michael V Johnston; Juan C Troncoso; J. Mark Redmond; William A Baumgartner

2001-01-01

141

Voice Over IP Curriculum  

NSDL National Science Digital Library

The Convergence Technology Center has made Voice over IP curriculum available online. The site includes a syllabus and learning activities related to the topic. If you are an educator who would like to gain full access to the complete curriculum, you may email convergence_technology@collin.edu (further instructions for access are available on the site).

2012-10-02

142

Health and Nutrition: Preconditions for Educational Achievement.  

ERIC Educational Resources Information Center

This paper discusses the importance of maternal and infant health for children's educational achievement. Education, health, and nutrition are so closely related that changes in one causes changes in the others. Improvement of maternal and preschooler health and nutrition is a precondition for improved educational achievement. Although parental…

Negussie, Birgit

143

Acceleration of TDP43 and FUS/TLS protein expressions in the preconditioned hippocampus following repeated transient ischemia.  

PubMed

The 43-kDa transactivation response DNA binding protein (TDP43), fused in sarcoma/translocated in liposarcoma (FUS/TLS), heat shock protein 70 (HSP70), and ?-amyloid (A?) are induced and involved in cerebral ischemia, amyotrophic lateral sclerosis (ALS), and Alzheimer's disease (AD), but their relationships in ischemic tolerance have never been examined, although they could be involved in endogenous neuroprotection under ischemic preconditioning. In the present study, Mongolian gerbils were subjected to one or three incidents of basically nonlethal 2-min transient common carotid arteries occlusion (tCCAO). Hippocampal CA1 neurons were lost only in the 2-min three times group at 3 and 7 days, which then gradually recovered from 1 to 6 months. Inductions of TDP43 and FUS/TLS were accelerated from 3 months to 7 days or from 7 days to 1 day, respectively, after 2-min three times ischemia compared with once. The cytoplasmic stainings of TDP43 and FUS/TLS showed a further acceleration of the peaks from 1 months to 3 days or from 1 months to 7 days, respectively, after 2-min three times ischemia compared with once. In contrast, HSP70 was induced only at 7 days after 2-min tCCAO for three times, with no expression for A?. These data show that ischemic preconditioning offers a way to induce endogenous neuroprotection and neurogenesis in gerbils, with TDP43, FUS/TLS, and HSP70 involved in this function. PMID:24265138

Sun, Miao; Yamashita, Toru; Shang, Jingwei; Liu, Ning; Deguchi, Kentaro; Liu, Wentao; Ikeda, Yoshio; Feng, Juan; Abe, Koji

2014-01-01

144

Tolerance-Inducing Dose of 3-Nitropropionic Acid Modulates bcl-2 and bax Balance in the Rat Brain: A Potential Mechanism of Chemical Preconditioning  

Microsoft Academic Search

Many studies have reported ischemia protection using various preconditioning techniques, including single dose 3-nitropropionic acid (3-NPA), a mitochondrial toxin. However, the cellular signal transduction cascades resulting in ischemic tolerance and the mechanisms involved in neuronal survival in the tolerant state still remain unclear. The current study investigated the mRNA and protein expression of the antiapoptotic bcl-2 and the proapoptotic bax,

Ansgar M Brambrink; Armin Schneider; Holger Noga; Andreas Astheimer; Bernhard Götz; Ines Körner; Axel Heimann; Martin Welschof; Oliver Kempski

2000-01-01

145

IP Addressing and RoutingIP Addressing and Routing TCP/IP Protocol SuiteTCP/IP Protocol Suite  

E-print Network

implementations still do) #12;7 ICMP Message FormatICMP Message Format 8-bit type of message 8-bit error code 16 Suite TCP UDP ICMP IP IGMP ARP RARP Ethernet #12;3 IP Packet FormatIP Packet Format Version HLen TOS Length Ident Flags Offset TTL Protocol Checksum SourceAddr DestinationAddr Options (variable) Pad

Yeom, Ikjun

146

Role of connexins and pannexins in ischemic stroke.  

PubMed

Synaptic plasticity requires careful synchronization and coordination of neurons and glial cells via various mechanisms of intercellular communication. Among them, are those mediated by i) connexin gap junction channels (GJCs), ii) connexin hemichannels and iii) pannexin channels. Whereas GJCs directly communicate the cytoplasm of contacting cells and coordinate electric and metabolic activities, connexin hemichannels and pannexin channels serve as diffusional pathways for ions and small molecules between the intra- and extracellular compartments. A growing body of evidence has revealed that intercellular communication could be critical in the spread of protective and/or deleterious signals during stroke. Here, we review current findings on the regulation of connexin- and pannexin-based channels in ischemic stroke and how they contribute to cell damage observed in pathology. Depending on intensity of the ischemic event, brain region and connexin subtype expressed, GJCs may provide proper diffusion of energy metabolites and dissipation of toxic substances, whereas, in other circumstances, they could increase damage by spreading toxic molecules. Alternatively, connexin hemichannel and pannexin channel opening may favor the release of neurotoxic substances (e.g., glutamate), but in other cases, they may confer neuroprotection against an ischemic episode by the phenomenon of ischemic preconditioning. Development of new drug modulators using in silico devices for connexin and pannexin-based channels will be crucial for future therapies against stroke. PMID:24372216

Orellana, J A; Avendaño, B C; Montero, T D

2014-01-01

147

Regeneration through autologous hypoxia preconditioned plasma  

PubMed Central

Cellular hypoxic preconditioning is being employed to obtain complex, yet physiological, secretomes rich is angiogenic factors. We previously proposed exposing peripheral blood cells (PBCs) to hypoxic stress stimulation, and demonstrated that controlled release of PBC-derived factor mixtures induces directional microvessel growth in vitro. Hypoxia therefore provides a useful tool for enhancing the angiogenic potential of blood plasma, by generating compositions based on PBCs' natural responses to a wound-like microenvironment. Here, we discuss various methods for preparing and delivering Hypoxia Preconditioned Plasma (HPP), i.e., plasma derived after extracorporeal conditioning of anticoagulated blood under physiological temperature and hypoxia. Special emphasis is given to those approaches that will likely facilitate the clinical translation of HPP-based therapies. We finally draw a comparison between HPP and other, currently available blood-based products, and present the case that its arrival paves the way for developing next-generation autologous therapies toward angiogenesis-supported tissue repair and regeneration. PMID:24831225

Hadjipanayi, Ektoras; Schilling, Arndt F

2014-01-01

148

Microarray Analyses of Genes Regulated by Isoflurane Anesthesia In Vivo: A Novel Approach to Identifying Potential Preconditioning Mechanisms  

PubMed Central

Background While general anesthetics are recognized for their potential to render patients unconscious during surgery, exposure can also lead to long-term outcomes of both cellular damage and protection. As regards the latter, delayed anesthetic preconditioning is an evolutionarily conserved physiological response that has the potential for protecting against ischemic injury in a number of tissues. While it is known that delayed preconditioning requires de novo protein synthesis, knowledge of anesthetic-regulated genes is incomplete. In this study we used the conserved nature of preconditioning to analyze differentially regulated genes in three different rat tissues. We hypothesized that by selecting those genes regulated in multiple tissues, we could develop a focused list of gene candidates potentially involved in delayed anesthetic preconditioning. Methods Young adult male Sprague Dawley rats were anesthetized with a 2% isoflurane/98% air mixture for 90 min. Immediately after anesthetic exposure, animals were killed and liver, kidney and heart were removed and total RNA was isolated. Differential gene expression was determined using rat oligonucleotide gene arrays. Array data were analyzed to select for genes that were significantly regulated in multiple tissues. Results All three tissues showed differentially regulated genes in response to a clinically relevant exposure to isoflurane. Analysis of coordinately regulated genes yielded a focused list of 34 potential gene candidates with a range of ontologies including regulation of inflammation, modulation of apoptosis, regulation of ion gradients and maintenance of energy pathways. Conclusions We conclude that, through using an analysis approach focusing on coordinately regulated genes, we were able to generate a focused list of interesting gene candidates with potential to enable future preconditioning studies. PMID:23400992

Edmands, Scott D; Hall, Adam C.; LaDow, Eva

2012-01-01

149

M-step preconditioned conjugate gradient methods  

NASA Technical Reports Server (NTRS)

Preconditioned conjugate gradient methods for solving sparse symmetric and positive finite systems of linear equations are described. Necessary and sufficient conditions are given for when these preconditioners can be used and an analysis of their effectiveness is given. Efficient computer implementations of these methods are discussed and results on the CYBER 203 and the Finite Element Machine under construction at NASA Langley Research Center are included.

Adams, L.

1983-01-01

150

A Recommendation System for Preconditioned Iterative Solvers  

E-print Network

December 2009 Major Subject: Computer Science A RECOMMENDATION SYSTEM FOR PRECONDITIONED ITERATIVE SOLVERS A Dissertation by THOMAS GEORGE Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of DOCTOR OF PHILOSOPHY Approved by: Chair of Committee, Vivek Sarin Committee Members, Patrick Lynett Valerie Taylor Yoonsuck Choe Head of Department, Valerie Taylor December 2009 Major Subject: Computer Science iii ABSTRACT A Recommendation...

George, Thomas

2011-02-22

151

Rock preconditioning to prevent rock bursts  

SciTech Connect

A US Bureau of Mines method to precondition rocks to prevent rock bursts is presented. The approach uses deep drill holes from a mine opening in a radial pattern in the vein and load and blast to fracture the rock prior to production mining. The method was successfully tested on a sphalerite-galena vein in a hard gangue of quartz and quartzite at the 7700 level of the Hecla Mining Company's Star Mine in Burke, Idaho. (JMT)

Not Available

1981-05-01

152

CANOPEN Controller IP Core  

NASA Astrophysics Data System (ADS)

This paper will describe the activities performed by Thales Alenia Space Italia supported by the European Space Agency in the definition of a CAN bus interface to be used on Exomars. The final goal of this activity is the development of an IP core, to be used in a slave node, able to manage both the CAN bus Data Link and Application Layer totally in hardware. The activity has been focused on the needs of the EXOMARS mission where devices with different computational performances are all managed by the onboard computer through the CAN bus.

Caramia, M.; Montagna, M.; Furano, G.; Winton, A.

2010-08-01

153

Preconditioning with Endoplasmic Reticulum Stress Ameliorates Endothelial Cell Inflammation  

PubMed Central

Endoplasmic Reticulum (ER) stress, caused by disturbance in ER homeostasis, has been implicated in several pathological conditions such as ischemic injury, neurodegenerative disorders, metabolic diseases and more recently in inflammatory conditions. Our present study aims at understanding the role of ER stress in endothelial cell (EC) inflammation, a critical event in the pathogenesis of acute lung injury (ALI). We found that preconditioning human pulmonary artery endothelial cells (HPAEC) to ER stress either by depleting ER chaperone and signaling regulator BiP using siRNA, or specifically cleaving (inactivating) BiP using subtilase cytotoxin (SubAB), alleviates EC inflammation. The two approaches adopted to abrogate BiP function induced ATF4 protein expression and the phosphorylation of eIF2?, both markers of ER stress, which in turn resulted in blunting the activation of NF-?B, and restoring endothelial barrier integrity. Pretreatment of HPAEC with BiP siRNA inhibited thrombin-induced I?B? degradation and its resulting downstream signaling pathway involving NF-?B nuclear translocation, DNA binding, phosphorylation at serine536, transcriptional activation and subsequent expression of adhesion molecules. However, TNF?-mediated NF-?B signaling was unaffected upon BiP knockdown. In an alternative approach, SubAB-mediated inactivation of NF-?B was independent of I?B? degradation. Mechanistic analysis revealed that pretreatment of EC with SubAB interfered with the binding of the liberated NF-?B to the DNA, thereby resulting in reduced expression of adhesion molecules, cytokines and chemokines. In addition, both knockdown and inactivation of BiP stimulated actin cytoskeletal reorganization resulting in restoration of endothelial permeability. Together our studies indicate that BiP plays a central role in EC inflammation and injury via its action on NF-?B activation and regulation of vascular permeability. PMID:25356743

Leonard, Antony; Paton, Adrienne W.; El-Quadi, Monaliza; Paton, James C.; Fazal, Fabeha

2014-01-01

154

Differential Temporal Evolution Patterns in Brain Temperature in Different Ischemic Tissues in a Monkey Model of Middle Cerebral Artery Occlusion  

PubMed Central

Brain temperature is elevated in acute ischemic stroke, especially in the ischemic penumbra (IP). We attempted to investigate the dynamic evolution of brain temperature in different ischemic regions in a monkey model of middle cerebral artery occlusion. The brain temperature of different ischemic regions was measured with proton magnetic resonance spectroscopy (1H MRS), and the evolution processes of brain temperature were compared among different ischemic regions. We found that the normal (baseline) brain temperature of the monkey brain was 37.16°C. In the artery occlusion stage, the mean brain temperature of ischemic tissue was 1.16°C higher than the baseline; however, this increase was region dependent, with 1.72°C in the IP, 1.08°C in the infarct core, and 0.62°C in the oligemic region. After recanalization, the brain temperature of the infarct core showed a pattern of an initial decrease accompanied by a subsequent increase. However, the brain temperature of the IP and oligemic region showed a monotonously and slowly decreased pattern. Our study suggests that in vivo measurement of brain temperature could help to identify whether ischemic tissue survives. PMID:23091367

Sun, Zhihua; Zhang, Jing; Chen, Yingmin; Zhang, Yunting; Zhang, Xuejun; Guo, Hong; Yu, Chunshui

2012-01-01

155

Preconditioning and the limit to the incompressible flow equations  

NASA Technical Reports Server (NTRS)

The use of preconditioning methods to accelerate the convergence to a steady state for both the incompressible and compressible fluid dynamic equations are considered. The relation between them for both the continuous problem and the finite difference approximation is also considered. The analysis relies on the inviscid equations. The preconditioning consists of a matrix multiplying the time derivatives. Hence, the steady state of the preconditioned system is the same as the steady state of the original system. For finite difference methods the preconditioning can change and improve the steady state solutions. An application to flow around an airfoil is presented.

Turkel, E.; Fiterman, A.; Vanleer, B.

1993-01-01

156

Ischemic ulcers - self-care  

MedlinePLUS

Ischemic ulcers (wounds) can occur when there is poor blood flow in your legs . Poor blood flow causes cells to die and damages tissue. Most ischemic ulcers occur on the feet and legs. These types ...

157

Ischemic Stroke and Neuroprotection  

PubMed Central

Stroke is a major cause of morbidity and mortality in both developed and developing countries of the world. Greater understanding of the pathophysiology of neuronal damage in ischemic stroke has generated interest in neuroprotection as a management strategy. This paper aims to review the current concept and place of neuroprotection in ischemic stroke. An extensive search of all materials related to the topic was made using library sources including Pubmed and Medline searches. Current research findings were also included. The findings are as presented. Neuroprotection is an increasingly recognized management strategy in ischemic stroke that promises to assist clinicians in reducing stroke mortality rates and improving the quality of life of survivors. PMID:23439855

Onwuekwe, IO; Ezeala-Adikaibe, B

2012-01-01

158

SIMPLE MACHINE PERFUSION SIGNIFICANTLY ENHANCES HEPATOCYTE YIELDS OF ISCHEMIC AND FRESH RAT LIVERS  

PubMed Central

The scarcity of viable hepatocytes is a significant bottleneck in cell transplantation, drug discovery, toxicology, tissue engineering, and bioartificial assist devices, where trillions of high-functioning hepatocytes are needed annually. We took the novel approach of using machine perfusion to maximize cell recovery, specifically from uncontrolled cardiac death donors, the largest source of disqualified donor organs. In a rat model, we developed a simple 3 hour room temperature (20±2°C) machine perfusion protocol to treat non-premedicated livers exposed to 1 hour of warm (34°C) ischemia. Treated ischemic livers were compared to fresh, fresh-treated and untreated ischemic livers using viable hepatocyte yields and in vitro performance as quantitative endpoints. Perfusion treatment resulted in both a 25-fold increase in viable hepatocytes from ischemic livers, and a 40% increase from fresh livers. While cell morphology and function in suspension and plate cultures of untreated warm ischemic cells was significantly impaired, treated warm ischemic cells were indistinguishable from fresh hepatocytes. Further, a strong linear correlation between tissue ATP and cell yield enabled accurate evaluation of the extent of perfusion recovery. Maximal recovery of warm ischemic liver ATP content appears to be correlated with optimal flow through the microvasculature. These data demonstrate that the inclusion of a simple perfusion-preconditioning step can significantly increase the efficiency of functional hepatocyte yields and the number of donor livers that can be gainfully utilized.

Izamis, Maria-Louisa; Calhoun, Candice; Uygun, Basak E.; Guzzardi, Maria Angela; Price, Gavrielle; Luitje, Martha; Saeidi, Nima; Yarmush, Martin L.; Uygun, Korkut

2014-01-01

159

Toward the Optimal Preconditioned Eigensolver: Locally Optimal Block Preconditioned Conjugate Gradient Method  

Microsoft Academic Search

We describe new algorithms of the locally optimal block preconditioned conjugate gradient (LOBPCG) method for symmetric eigenvalue problems, based on a local optimization of a three-term recurrence, and suggest several other new methods. To be able to compare numerically different methods in the class, with different preconditioners, we propose a common system of model tests, using random preconditioners and initial

Andrew V. Knyazev

2001-01-01

160

Domain-decomposed preconditionings for transport operators  

NASA Technical Reports Server (NTRS)

The performance was tested of five different interface preconditionings for domain decomposed convection diffusion problems, including a novel one known as the spectral probe, while varying mesh parameters, Reynolds number, ratio of subdomain diffusion coefficients, and domain aspect ratio. The preconditioners are representative of the range of practically computable possibilities that have appeared in the domain decomposition literature for the treatment of nonoverlapping subdomains. It is shown that through a large number of numerical examples that no single preconditioner can be considered uniformly superior or uniformly inferior to the rest, but that knowledge of particulars, including the shape and strength of the convection, is important in selecting among them in a given problem.

Chan, Tony F.; Gropp, William D.; Keyes, David E.

1991-01-01

161

Voice Over IP Reference Page  

NSDL National Science Digital Library

This site is a collection of architectural specifications, network and signaling protocols, and technical papers related to virtually every aspect of VoIP. Detailed articles and standards information are regularly updated on the site. There is also a collection of documents containing VoIP references, and in this sections, visitors will find an H.323 tutorial.

2008-02-13

162

Ischemic conditioning: the challenge of protecting the diabetic heart  

PubMed Central

The successful clinical translation of novel therapeutic strategies to attenuate lethal myocardial ischemia-reperfusion injury and limit infarct size has been identified as a major unmet need, and is of particular importance in patients with type-2 diabetes. There is a wealth of preclinical evidence that ischemic conditioning (encompassing the three paradigms of preconditioning, postconditioning and remote conditioning) is profoundly cardioprotective and, via up-regulation of endogenous signaling cascades, renders the heart resistant to infarction. However, current phase II trials aimed at exploiting ischemic conditioning for the clinical treatment of myocardial ischemia-reperfusion injury have yielded mixed results, possibly reflecting the emerging concern that the efficacy of conditioning-induced cardioprotection may be compromised in the diabetic heart. Our goal in this review is to provide a summary of our present understanding of the effect of type-2 diabetes on the infarct-sparing effect of ischemic conditioning, and the challenges of limiting ischemia-reperfusion injury in the diabetic heart.

Wider, Joseph

2014-01-01

163

Ischemic Nerve Block.  

ERIC Educational Resources Information Center

This experiment investigated the capability for movement and muscle spindle function at successive stages during the development of ischemic nerve block (INB) by pressure cuff. Two male subjects were observed under six randomly ordered conditions. The duration of index finger oscillation to exhaustion, paced at 1.2Hz., was observed on separate…

Williams, Ian D.

164

Hypertriglyceridemia and Ischemic Stroke  

Microsoft Academic Search

There are no conclusive data regarding the association between dyslipidemia and the risk of ischemic stroke (IS). Clinical investigations have primarily focused on the association between elevated levels of low-density lipoprotein cholesterol and low levels of high-density lipoprotein cholesterol as stroke risk factors. Much less scientific attention has been aimed at elevated levels of triglycerides. Consequently the potential role of

Nader Antonios; Dominick J. Angiolillo; Scott Silliman

2008-01-01

165

Fast Radial Basis Function Interpolation via Preconditioned Krylov Iteration  

Microsoft Academic Search

We consider a preconditioned Krylov subspace iterative algorithm presented by Faul et al. (IMA Journal of Numerical Analysis (2005) 25, 1—24) for computing the coefficients of a radial basis function interpolant over N data points. This preconditioned Krylov iteration has been demonstrated to be extremely robust and the iteration rapidly convergent. However, the iterative method has several steps whose computational

Nail A. Gumerov; Ramani Duraiswami

2007-01-01

166

Education for Social Responsibility: Preconditions in Retrospect and in Prospect.  

ERIC Educational Resources Information Center

One of the purposes of professional education is to educate professionals to honor their social responsibility. This paper presents three stories that identify important preconditions in education for social responsibility. The preconditions include socially responsive faculty and field integrity. Each story includes morals (i.e., lessons about…

Lawson, Hal A.

1999-01-01

167

IP Watermarking Techniques: Survey and Comparison  

E-print Network

blocks in such a competitive market poses significant high security risks. IPs can be read, copied designs. Sharing IP designs poses significant high security risks. Most of these IPs need time and effort property (IP) block reuse is essential for facilitating the design process of System-on-a-Chip. Sharing IP

Tahar, Sofiène

168

Traditional IP Measurements: What Changes in a Today Multimedia IP Network  

E-print Network

IP architecture and delivers to the user data, VoIP and IPTV services over a single broadbandIP and IPTV traffic instead presents periodicities of the packet arrival process, due to periodicity by several research groups [5], [6], [7]. Today, Voice over IP (VoIP) and IP television (IPTV) technologies

169

Hypoxic Preconditioning Differentially Affects GABAergic and Glutamatergic Neuronal Cells in the Injured Cerebellum of the Neonatal Rat  

PubMed Central

In this study we examined cerebellar alterations in a neonatal rat model of hypoxic-ischemic brain injury with or without hypoxic preconditioning (Pc). Between postnatal days 7 and 15, the cerebellum is still undergoing intense cellular proliferation, differentiation and migration, dendritogenesis and synaptogenesis. The expression of glutamate decarboxylase 1 (GAD67) and the differentiation factor NeuroD1 were examined as markers of Purkinje and granule cells, respectively. We applied quantitative immunohistochemistry to sagittal cerebellar slices, and Western blot analysis of whole cerebella obtained from control (C) rats and rats submitted to Pc, hypoxia-ischemia (L) and a combination of both treatments (PcL). We found that either hypoxia-ischemia or Pc perturbed the granule cells in the posterior lobes, affecting their migration and final placement in the internal granular layer. These effects were partially attenuated when the Pc was delivered prior to the hypoxia-ischemia. Interestingly, whole nuclear NeuroD1 levels in Pc animals were comparable to those in the C rats. However, a subset of Purkinje cells that were severely affected by the hypoxic-ischemic insult—showing signs of neuronal distress at the levels of the nucleus, cytoplasm and dendritic arborization—were not protected by Pc. A monoclonal antibody specific for GAD67 revealed a three-band pattern in cytoplasmic extracts from whole P15 cerebella. A ?110 kDa band, interpreted as a potential homodimer of a truncated form of GAD67, was reduced in Pc and L groups while its levels were close to the control animals in PcL rats. Additionally we demonstrated differential glial responses depending on the treatment, including astrogliosis in hypoxiated cerebella and a selective effect of hypoxia-ischemia on the vimentin-immunolabeled intermediate filaments of the Bergmann glia. Thus, while both glutamatergic and GABAergic cerebellar neurons are compromised by the hypoxic-ischemic insult, the former are protected by a preconditioning hypoxia while the latter are not. PMID:25032984

Patterson, Sean I.; Muñoz, Estela M.; Seltzer, Alicia M.

2014-01-01

170

A fast, preconditioned conjugate gradient Toeplitz solver  

NASA Technical Reports Server (NTRS)

A simple factorization is given of an arbitrary hermitian, positive definite matrix in which the factors are well-conditioned, hermitian, and positive definite. In fact, given knowledge of the extreme eigenvalues of the original matrix A, an optimal improvement can be achieved, making the condition numbers of each of the two factors equal to the square root of the condition number of A. This technique is to applied to the solution of hermitian, positive definite Toeplitz systems. Large linear systems with hermitian, positive definite Toeplitz matrices arise in some signal processing applications. A stable fast algorithm is given for solving these systems that is based on the preconditioned conjugate gradient method. The algorithm exploits Toeplitz structure to reduce the cost of an iteration to O(n log n) by applying the fast Fourier Transform to compute matrix-vector products. Matrix factorization is used as a preconditioner.

Pan, Victor; Schrieber, Robert

1989-01-01

171

Causes of Ischemic Stroke  

Microsoft Academic Search

\\u000a Ischemic stroke is a heterogeneous disease and occurs due to a multitude of underlying pathologic processes. The brain is\\u000a such an exquisitely sensitive reporting system that small infarctions, well below the size that causes clinical signs in other\\u000a organ systems, can cause major disability in the brain. About 85% of all strokes are due to ischemia, and in the majority

Gisele S. Silva; Walter J. Koroshetz; R. Gilberto González; Lee H. Schwamm

172

Acute ischemic stroke  

Microsoft Academic Search

Opinion statement  Patients with acute ischemic stroke should be immediately transported to the nearest hospital for rapid evaluation and treatment.\\u000a Intravenous t-PA within 3 hours of symptom onset is the recommended treatment for patients who meet the National Institute\\u000a of Neurological Disorders and Stroke (NINDS) study eligibility criteria. Patients should be informed of the risk of symptomatic\\u000a cerebral hemorrhage, and strict

Bernard P. Chan; Gregory W. Albers

1999-01-01

173

Hyperbaric oxygen preconditioning attenuates postoperative cognitive impairment in aged rats.  

PubMed

Cognitive decline after surgery in the elderly population is a major clinical problem with high morbidity. Hyperbaric oxygen (HBO) preconditioning can induce significant neuroprotection against acute neurological injury. We hypothesized that HBO preconditioning would prevent the development of postoperative cognitive impairment. Elderly male rats (20 months old) underwent stabilized tibial fracture operation under general anesthesia after HBO preconditioning (once a day for 5 days). Separate cohorts of animals were tested for cognitive function with fear conditioning and Y-maze tests, or euthanized at different times to assess the blood-brain barrier integrity, systemic and hippocampal proinflammatory cytokines, and caspase-3 activity. Animals exhibited significant cognitive impairment evidenced by a decreased percentage of freezing time and an increased number of learning trials on days 1, 3, and 7 after surgery, which were significantly prevented by HBO preconditioning. Furthermore, HBO preconditioning significantly ameliorated the increase in serum and hippocampal proinflammatory cytokines tumor necrosis factor-?, interleukin-1 ? (IL-1?), IL-6, and high-mobility group protein 1 in surgery-challenged animals. Moreover, HBO preconditioning markedly improved blood-brain barrier integrity and caspase-3 activity in the hippocampus of surgery-challenged animals. These findings suggest that HBO preconditioning could significantly mitigate surgery-induced cognitive impairment, which is strongly associated with the reduction of systemic and hippocampal proinflammatory cytokines and caspase-3 activity. PMID:24870985

Sun, Li; Xie, Keliang; Zhang, Changsheng; Song, Rui; Zhang, Hong

2014-06-18

174

IP Version 6, Online Version  

NSDL National Science Digital Library

This page offers five videos of lectures from Sam Bowne's IP Version 6 course. Each video varies in length from ten minutes to an hour. These materials would be most useful for individuals with some experience with IP technology; the end goal of the course was for individuals enrolled to gain IPv6 certification and be able to set up IPv6 on a router. Flash is required to view the videos.

Bowne, Sam

2012-10-17

175

Protein Redox Modification as a Cellular Defense Mechanism against Tissue Ischemic Injury  

PubMed Central

Protein oxidative or redox modifications induced by reactive oxygen species (ROS) or reactive nitrogen species (RNS) not only can impair protein function, but also can regulate and expand protein function under a variety of stressful conditions. Protein oxidative modifications can generally be classified into two categories: irreversible oxidation and reversible oxidation. While irreversible oxidation usually leads to protein aggregation and degradation, reversible oxidation that usually occurs on protein cysteine residues can often serve as an “on and off” switch that regulates protein function and redox signaling pathways upon stress challenges. In the context of ischemic tolerance, including preconditioning and postconditioning, increasing evidence has indicated that reversible cysteine redox modifications such as S-sulfonation, S-nitrosylation, S-glutathionylation, and disulfide bond formation can serve as a cellular defense mechanism against tissue ischemic injury. In this review, I highlight evidence of cysteine redox modifications as protective measures in ischemic injury, demonstrating that protein redox modifications can serve as a therapeutic target for attenuating tissue ischemic injury. Prospectively, more oxidatively modified proteins will need to be identified that can play protective roles in tissue ischemic injury, in particular, when the oxidative modifications of such identified proteins can be enhanced by pharmacological agents or drugs that are available or to be developed. PMID:24883175

Yan, Liang-Jun

2014-01-01

176

Protection of the ischemic myocardium during the reperfusion: between hope and reality  

PubMed Central

The heart is an organ that requires an important energy input to ensure its contractile function. Myocardial ischemia happens when there is a deficiency of blood flow that is responsible for the passage from an aerobic to anaerobic metabolism. Myocardial ischemia results from an imbalance between inputs and the needs of nutrient and oxygen to the myocardium. The restoration of myocardial perfusion called reperfusion is a way to save the ischemic myocardium. However, although reperfusion is beneficial for the survival of the ischemic myocardium, it also induces a deleterious effect in addition to that of ischemic stress. Three decade ago, while several studies, strived to elucidate the protective effect of preconditioning, a phenomenon performed before ischemia and having a powerful protective effects against ischemia/reperfusion injury, very few have believed in the possibility of protecting the myocardium after ischemia (during reperfusion). Actually, both ischemic and pharmacological postconditioning as well as controlled reperfusion methods to protect the ischemic heart have proved effective in the reduction of damage related to ischemia/reperfusion. The possibility of protecting the myocardium during reperfusion opens a new area in the research against damage caused by ischemia/reperfusion because these methods are easily transferable in a clinic setting. PMID:22937492

Bopassa, Jean Chrisostome

2012-01-01

177

Reactive oxygen species are not a required trigger for exercise-induced late preconditioning in the rat heart.  

PubMed

Reactive oxygen species (ROS) have been reported to play a primary role in triggering the cardioprotective adaptations by some preconditioning procedures, but whether they are required for exercise-induced preconditioning is unclear. Thus in this study we used the free radical scavenger N-(2-mercaptopropionyl)glycine (MPG) to test the hypothesis that ROS is the trigger for exercise-induced preconditioning of the heart against ischemia-reperfusion injury. Male F344 rats were assigned to four groups: sedentary (SED, n = 7), SED/MPG (100 mg/kg ip daily for 2 days, n = 12), exercised on a treadmill for 2 days at 20 m/min, 6° grade, for 60 min (RUN, n = 7), and RUN/MPG with 100 mg/kg MPG injected 15 min before exercise (n = 10). Preliminary experiments verified that MPG administration maintained myocardial redox status during the exercise bout. Twenty-four hours postexercise or MPG treatment isolated perfused working hearts were subjected to global ischemia for 22.5 min followed by reperfusion for 30 min. Recovery of myocardial external work (percentage of preischemic systolic pressure times cardiac output) for SED (50.4 ± 4.5) and SED/RUN (54.7 ± 6.6) was similar and improved in both exercise groups (P < 0.05) to 77.9 ± 3.0 in RUN and 76.7 ± 4.5 in RUN/MPG. A 2 × 2 ANOVA also revealed that exercise decreased lactate dehydrogenase release from the heart during reperfusion (marker of cell damage) without MPG effects or interactions. Expression of the cytoprotective protein inducible heat shock protein 70 increased by similar amounts in the left ventricles of RUN and RUN/MPG compared with sedentary groups (P < 0.05). We conclude that ROS are not a necessary trigger for exercise-induced preconditioning in rats. PMID:22955056

Taylor, Ryan P; Starnes, Joseph W

2012-11-01

178

Running TCP/IP over ATM Networks.  

ERIC Educational Resources Information Center

Discusses Internet protocol (IP) and subnets and describes how IP may operate over asynchronous transfer mode (ATM). Topics include TCP (transmission control protocol), ATM cells and adaptation layers, a basic architectural model for IP over ATM, address resolution, mapping IP to a subnet technology, and connection management strategy. (LRW)

Witt, Michael

1995-01-01

179

Network Terminology TCP/IP Network Layers  

E-print Network

Network Terminology TCP/IP Network Layers Socket Programming Data Communication and Computer;Network Terminology TCP/IP Network Layers Socket Programming 1 Network Terminology 2 TCP/IP Network Layers TCP/IP vs OSI 3 Socket Programming Opening a Socket Bind, Listen, Accept Connect, Send, Recv

Ramkumar, Mahalingam

180

The Mitochondria-Targeted Antioxidants and Remote Kidney Preconditioning Ameliorate Brain Damage through Kidney-to-Brain Cross-Talk  

PubMed Central

Background Many ischemia-induced neurological pathologies including stroke are associated with high oxidative stress. Mitochondria-targeted antioxidants could rescue the ischemic organ by providing specific delivery of antioxidant molecules to the mitochondrion, which potentially suffers from oxidative stress more than non-mitochondrial cellular compartments. Besides direct antioxidative activity, these compounds are believed to activate numerous protective pathways. Endogenous anti-ischemic defense may involve the very powerful neuroprotective agent erythropoietin, which is mainly produced by the kidney in a redox-dependent manner, indicating an important role of the kidney in regulation of brain ischemic damage. The goal of this study is to track the relations between the kidney and the brain in terms of the amplification of defense mechanisms during SkQR1 treatment and remote renal preconditioning and provide evidence that the kidney can generate signals inducing a tolerance to oxidative stress-associated brain pathologies. Methodology/Principal Findings We used the cationic plastoquinone derivative, SkQR1, as a mitochondria-targeted antioxidant to alleviate the deleterious consequences of stroke. A single injection of SkQR1 before cerebral ischemia in a dose-dependent manner reduces infarction and improves functional recovery. Concomitantly, an increase in the levels of erythropoietin in urine and phosphorylated glycogen synthase kinase-3? (GSK-3?) in the brain was detected 24 h after SkQR1 injection. However, protective effects of SkQR1 were not observed in rats with bilateral nephrectomy and in those treated with the nephrotoxic antibiotic gentamicin, indicating the protective role of humoral factor(s) which are released from functional kidneys. Renal preconditioning also induced brain protection in rats accompanied by an increased erythropoietin level in urine and kidney tissue and P-GSK-3? in brain. Co-cultivation of SkQR1-treated kidney cells with cortical neurons resulted in enchanced phosphorylation of GSK-3? in neuronal cells. Conclusion The results indicate that renal preconditioning and SkQR1-induced brain protection may be mediated through the release of EPO from the kidney. PMID:23272118

Silachev, Denis N.; Isaev, Nikolay K.; Pevzner, Irina B.; Zorova, Ljubava D.; Stelmashook, Elena V.; Novikova, Svetlana V.; Plotnikov, Egor Y.; Skulachev, Vladimir P.; Zorov, Dmitry B.

2012-01-01

181

Ischemic pretreatment delays ischemic brain vasospasm injury in gerbils.  

PubMed

Three experiments were conducted for the present study. First, to elucidate the mechanism and functional significance underlying ischemic vasoconstriction, we investigated the relationship between arteriolar constriction and tissue energy metabolism during bilateral common carotid artery occlusion in gerbils. Second, to identify differences in the postischemic recovery of physiologic parameters between short and prolonged brain ischemia, we measured changes in regional cerebral blood flow, microvessel diameter, brain temperature, and electrophysiologic response. Third, to explore the physiological mechanism of ischemic tolerance, we studied vascular response and intracerebral oxygenation states after acute global ischemia with and without pretreatment by mild ischemic stress. Here, we identify one of the physiologic mechanisms of the ischemic tolerance caused by brief ischemic pretreatment. PMID:24729240

Seiyama, Akitoshi; Yoshikawa, Nao; Imamura, Yukio

2014-01-01

182

Treatment of acute ischemic stroke  

Microsoft Academic Search

Acute ischemic stroke is the third leading cause of death in the United States and the leading cause of adult disability. The direct and indirect costs of stroke care exceed $51 billion annually. In 1996, the US Food and Drug Administration approved the first treatment for acute ischemic stroke, intravenous tissue plasminogen activator. Later that year, the National Institute of

Christopher Lewandowski; William Barsan

2001-01-01

183

Let's Talk about Ischemic Stroke  

MedlinePLUS

... diagnostic tests that might be needed How are ischemic strokes treated? Acute treatment is the immediate treatment given by the ... team when a stroke happens. The goal of acute treatment is to keep the amount ... drug to treat ischemic stroke is tissue plasminogen activator (tPA). It is ...

184

Raj JainThe Ohio State University TCP/IP ProtocolTCP/IP Protocol  

E-print Network

Raj JainThe Ohio State University 1 TCP/IP ProtocolTCP/IP Protocol Suite and State University 3 Key Differences From OSIKey Differences From OSI Connectionless Service: TCP/IP close all higher layers #12;Raj JainThe Ohio State University 6 TCP/IP ProtocolsTCP/IP Protocols Network

Jain, Raj

185

Chronic Tempol treatment restores pharmacological preconditioning in the senescent rat heart.  

PubMed

Cardioprotective effects of anesthetic preconditioning and cyclosporine A (CsA) are lost with aging. To extend our previous work and address a possible mechanism underlying age-related differences, we investigated the role of oxidative stress in the aging heart by treating senescent animals with the oxygen free radical scavenger Tempol. Old male Fischer 344 rats (22-24 mo) were randomly assigned to control or Tempol treatment groups for 2 or 4 wk (T×2wk and T×4wk, respectively). Rats received isoflurane 30 min before ischemia-reperfusion injury or CsA just before reperfusion. Myocardial infarction sizes were significantly reduced by isoflurane or CsA in the aged rats treated with Tempol (T×4wk) compared with old control rats. In other experiments, young (4-6 mo) and old rats underwent either chronic Tempol or vehicle treatment, and the levels of myocardial protein oxidative damage, antioxidant enzymes, mitochondrial Ca(2+) uptake, cyclophilin D protein, and mitochondrial permeability transition pore opening times were measured. T×4wk significantly increased MnSOD enzyme activity, GSH-to-GSSH ratios, MnSOD protein level, mitochondrial Ca(2+) uptake capacity, reduced protein nitrotyrosine levels, and normalized cyclophilin D protein expression in the aged rat heart. T×4wk also significantly prolonged mitochondrial permeability transition pore opening times induced by reactive oxygen species in old cardiomyocytes. Our studies demonstrate that 4 wk of Tempol pretreatment restores anesthetic preconditioning and cardioprotection by CsA in the old rat and that this is associated with decreased oxidative stress and improved mitochondrial function. Our results point to a new protective strategy for the ischemic myocardium in the high-risk older population. PMID:23275621

Zhu, Jiang; Rebecchi, Mario J; Wang, Qiang; Glass, Peter S A; Brink, Peter R; Liu, Lixin

2013-03-01

186

Intermittent aortic crossclamping prevents cumulative adenosine triphosphate depletion, ventricular fibrillation, and dysfunction (stunning): is it preconditioning?  

PubMed

This study was designed to determine whether intermittent warm aortic crossclamping induces cumulative myocardial stunning or if the myocardium becomes preconditioned after the first episode of ischemia in canine models in vivo. The role of adenosine triphosphate catabolism and subsequent release of purines on reperfusion-mediated postischemic ventricular dysfunction and arrhythmias was assessed with the use of selective inhibitors of nucleoside transport, p-nitrobenzylthioinosine (NBMPR), and a specific adenosine deaminase inhibitor, erythro-9-[2-hydroxy-3-nonyl] adenine (EHNA). Thirty-two anesthetized dogs were instrumented to monitor left ventricular contractility, off bypass, by sonomicrometry. During cardiopulmonary bypass dogs were treated before ischemia with either saline solution (control group, n = 8) or EHNA (100 mumol/L) and NBMPR (25 mumol/L) (EHNA/NBMPR group, n = 8). Hearts were subjected to either 60 minutes of global ischemia and 120 minutes of reperfusion (n = 16) or 6 episodes of 10 minutes of global ischemia and 10 minutes of reperfusion, followed by 60 minutes of reperfusion (n = 16). Sixty minutes of sustained ischemia resulted in 80% loss of adenosine triphosphate and induced reperfusion-mediated ventricular fibrillation and severe left ventricular dysfunction in the control group. EHNA/NBMPR treatment augmented myocardial adenosine trapping during ischemia, attenuated ventricular fibrillation, and enhanced left ventricular functional recovery, despite similar depletion of adenosine triphosphate (80% loss). In the intermittent ischemia experiment, the first episode of 10 minutes of ischemia and reperfusion caused significant adenosine triphosphate depletion, ventricular fibrillation, and left ventricular stunning in both control and drug-treated groups. The prevalence of ventricular fibrillation was greater in the control group than in the drug-treated group after the first episode of ischemia (p < 0.05). Adenosine was the major nucleoside accumulated in the myocardium at the end of 10 minutes of ischemia in the EHNA/NBMPR-treated group (p < 0.05 versus control). Subsequent episodes of ischemia prevented ventricular fibrillation and did not cause cumulative left ventricular stunning in either group. Left ventricular function fully recovered in the EHNA/NBMPR-treated group after intermittent ischemia, but remained stunned in the control group. Unlike sustained ischemia, intermittent ischemia and reperfusion preserved myocardial adenosine triphosphate, limited purine release, and prevented ventricular fibrillation and cumulative stunning. These results suggest that intermittent ischemia and reperfusion augmented the endogenous protective mechanism or mechanisms of "preconditioning." Nucleoside trapping improved functional recovery after sustained or repetitive ischemia. It is concluded that adenosine triphosphate preservation or blockade of nucleoside transport may play an important role in the activation of endogenous myocardial protective mechanisms that "precondition" against subsequent ischemic stress. PMID:7637350

Abd-Elfattah, A S; Ding, M; Wechsler, A S

1995-08-01

187

Compositional control of IP media  

Microsoft Academic Search

In many IP media services, the media chan- nels are point-to-point, dynamic, and set up with the par- ticipation of one or more application servers, even though the media packets themselves travel directly between media endpoints. The application servers must be programmed so that media behavior is globally correct, even though the servers may attempt to manipulate the same media

Pamela Zave; Eric Cheung

2006-01-01

188

Continuously Connected With Mobile IP  

NASA Technical Reports Server (NTRS)

Cisco Systems developed Cisco Mobile Networks, making IP devices mobile. With this innovation, a Cisco router and its connected IP devices can roam across network boundaries and connection types. Because a mobile user is able to keep the same IP address while roaming, a live IP connection can be maintained without interruption. Glenn Research Center jointly tested the technology with Cisco, and is working to use it on low-earth-orbiting research craft. With Cisco's Mobile Networks functionality now available in Cisco IOS Software release 12.2(4)T, the commercial advantages and benefits are numerous. The technology can be applied to public safety, military/homeland security, emergency management services, railroad and shipping systems, and the automotive industry. It will allow ambulances, police, firemen, and the U.S. Coast Guard to stay connected to their networks while on the move. In the wireless battlefield, the technology will provide rapid infrastructure deployment for U.S. national defense. Airline, train, and cruise passengers utilizing Cisco Mobile Networks can fly all around the world with a continuous Internet connection. Cisco IOS(R) Software is a registered trademark of Cisco Systems.

2002-01-01

189

Encrypted IP video communication system  

NASA Astrophysics Data System (ADS)

Digital video transmission is a permanent subject of development, research and improvement. This field of research has an exponentially growing market in civil, surveillance, security and military aplications. A lot of solutions: FPGA, ASIC, DSP have been used for this purpose. The paper presents the implementation of an encrypted, IP based, video communication system having a competitive performance/cost ratio .

Bogdan, Apetrechioaie; Lumini?a, Mateescu

2010-11-01

190

The Chronic Protective Effects of Limb Remote Preconditioning and the Underlying Mechanisms Involved in Inflammatory Factors in Rat Stroke  

PubMed Central

We recently demonstrated that limb remote preconditioning (LRP) protects against focal ischemia measured 2 days post-stroke. Here, we studied whether LRP provides long-term protection and improves neurological function. We also investigated whether LRP transmits its protective signaling via the afferent nerve pathways from the preconditioned limb to the ischemic brain and whether inflammatory factors are involved in LRP, including the novel galectin-9/Tim-3 inflammatory cell signaling pathway, which induces cell death in lymphocytes. LRP in the left hind femoral artery was performed immediately before stroke. LRP reduced brain injury size both at 2 days and 60 days post-stroke and improved behavioral outcomes for up to 2 months. The sensory nerve inhibitors capsaicin and hexamethonium, a ganglion blocker, abolished the protective effects of LRP. In addition, LRP inhibited edema formation and blood-brain barrier (BBB) permeability measured 2 days post-stroke. Western blot and immunostaining analysis showed that LRP inhibited protein expression of both galectin-9 and T-cell immunoglobulin domain and mucin domain 3 (Tim-3), which were increased after stroke. In addition, LRP decreased iNOS and nitrotyrosine protein expression after stroke. In conclusion, LRP executes long-term protective effects against stroke and may block brain injury by inhibiting activities of the galectin-9/Tim-3 pathway, iNOS, and nitrotyrosine. PMID:22347410

Chen, Xiaoyuan; Zhao, Heng

2012-01-01

191

[Cerebrolysin for acute ischemic stroke].  

PubMed

The review discusses existing evidence of benefits and risks of cerebrolysin--a mixture of low-molecular-weight peptides and amino acids derived from pigs' brain tissue with proposed neuroprotective and neurotrophic properties, for acute ischemic stroke. The review presents results of systematic search and analysis of randomised clinical trials comparing cerebrolysin with placebo in patients with acute ischemic stroke. Only one trial was selected as meeting quality criteria. No difference in death and adverse events between cerebrolysin and placebo was established. The authors conclude about insufficiency of evidence to evaluate the effect of cerebrolysin on survival and dependency in people with acute ischemic stroke. PMID:23805635

iganshina, L E; Abakumova, T R

2013-01-01

192

Implementation of Preconditioned Dual-Time Procedures in OVERFLOW  

NASA Technical Reports Server (NTRS)

Preconditioning methods have become the method of choice for the solution of flowfields involving the simultaneous presence of low Mach and transonic regions. It is well known that these methods are important for insuring accurate numerical discretization as well as convergence efficiency over various operating conditions such as low Mach number, low Reynolds number and high Strouhal numbers. For unsteady problems, the preconditioning is introduced within a dual-time framework wherein the physical time-derivatives are used to march the unsteady equations and the preconditioned time-derivatives are used for purposes of numerical discretization and iterative solution. In this paper, we describe the implementation of the preconditioned dual-time methodology in the OVERFLOW code. To demonstrate the performance of the method, we employ both simple and practical unsteady flowfields, including vortex propagation in a low Mach number flow, flowfield of an impulsively started plate (Stokes' first problem) arid a cylindrical jet in a low Mach number crossflow with ground effect. All the results demonstrate that the preconditioning algorithm is responsible for improvements to both numerical accuracy and convergence efficiency and, thereby, enables low Mach number unsteady computations to be performed at a fraction of the cost of traditional time-marching methods.

Pandya, Shishir A.; Venkateswaran, Sankaran; Pulliam, Thomas H.; Kwak, Dochan (Technical Monitor)

2003-01-01

193

Complications following Acute Ischemic Stroke  

Microsoft Academic Search

The objective of this study was to assess typical early-onset complications following ischemic stroke in a large, hospital-based cohort to provide clinical data for future randomized trials and quality standards in clinical routine. 3,866 patients with acute ischemic stroke were prospectively documented in 14 Neurology Departments with an acute stroke unit. Within the first week after admission, increased intracranial pressure

Christian Weimar; Michael P. Roth; Gesine Zillessen; Jörg Glahn; Martin L. J. Wimmer; Otto Busse; Roman L. Haberl; Hans-Christoph Diener

2002-01-01

194

Making the case for IPS supported employment.  

PubMed

Individual Placement and Support (IPS) is an evidence-based practice for helping people with severe mental illness (SMI) gain competitive employment, yet those who could benefit often find it difficult to obtain IPS services. We summarize the evidence supporting the effectiveness of IPS and the benefits of working, discuss the barriers to implementing IPS in the U.S., and suggest policy changes that could expand its access. PMID:23161326

Bond, Gary R; Drake, Robert E

2014-01-01

195

Operator-Based Preconditioning of Stiff Hyperbolic Systems  

SciTech Connect

We introduce an operator-based scheme for preconditioning stiff components encoun- tered in implicit methods for hyperbolic systems of partial differential equations posed on regular grids. The method is based on a directional splitting of the implicit operator, followed by a char- acteristic decomposition of the resulting directional parts. This approach allows for solution to any number of characteristic components, from the entire system to only the fastest, stiffness-inducing waves. We apply the preconditioning method to stiff hyperbolic systems arising in magnetohydro- dynamics and gas dynamics. We then present numerical results showing that this preconditioning scheme works well on problems where the underlying stiffness results from the interaction of fast transient waves with slowly-evolving dynamics, scales well to large problem sizes and numbers of processors, and allows for additional customization based on the specific problems under study.

Daniel R. Reynolds, Ravi Samtaney, and Carol S. Woodward

2009-02-09

196

Biological networks in ischemic tolerance - Rethinking the approach to clinical conditioning  

PubMed Central

The adaptive response (conditioning) to environmental stressors evokes evolutionarily conserved programs in uni- and multicellular organisms that result in increased fitness and resistance to stressor induced injury. Although the concept of conditioning has been around for a while, its translation into clinical therapies targeting neurovascular diseases has only recently begun. The slow pace of clinical adoption might be partially explained by our poor understanding of underpinning mechanisms and of the complex responses of the organism to the stressor. At the 2nd Translational Preconditioning Meeting participants engaged in an intense discussion addressing whether the time has come to more aggressively implement clinical conditioning protocols in the treatment of cerebrovascular diseases or whether it would be better to wait until preclinical data would help to minimize clinical empiricism. This review addresses the complex involvement of biological networks in establishing ischemic tolerance at the organism level using two clinically promising conditioning modalities, namely remote ischemic preconditioning, and per- or post-conditioning, as examples. PMID:24223074

Anrather, Josef; Hallenbeck, John M.

2013-01-01

197

VoIP Regulation in Latin America  

Microsoft Academic Search

Voice over IP (VoIP) is a disruptive technology that can be consider a menace to curr ent circuit-switched telephony operators. This paper studies the regulation that affects VoIP technology in Latin America. In order to carry out the analysis, the \\

Juan Rendón; Martha García-Murillo; Ana Villegas; Federico Kuhlmann

2007-01-01

198

PSAT: Proactive Signaling Architecture for IP Traceback  

Microsoft Academic Search

As the Internet becomes pervasive, the vulnerability of some fundamental design aspects of the Internet has also become relevant. The rising threat of cyber attacks makes the IP traceback problem very relevant to today's Internet security. Unfortunately, there is no easy way to track IP traffic to its source due to the stateless nature of the IP protocol, and to

Ahmad Fadlallah; Ahmed Serhrouchni

2006-01-01

199

Mahalingam Ramkumar TCP/IP Example  

E-print Network

IPsec Mahalingam Ramkumar #12;TCP/IP Example #12;IPv4 / IPv6 Compatible with both IPv4 and IPv6) AH 5) ESP 6) Dest. Options #12;IPsec IP Security (RFCs 2401, 2402, 2406) Secure IP layer Applications of IPSec ­ Secure branch office connectivity over the Internet ­ Secure remote access over

Ramkumar, Mahalingam

200

Human placental metabolic adaptation to chronic hypoxia, high altitude: hypoxic preconditioning  

PubMed Central

We have previously demonstrated placentas from laboring deliveries at high altitude have lower binding of hypoxia-inducible transcription factor (HIF) to DNA than those from low altitude. It has recently been reported that labor causes oxidative stress in placentas, likely due to ischemic hypoxic insult. We hypothesized that placentas of high-altitude residents acquired resistance, in the course of their development, to oxidative stress during labor. Full-thickness placental tissue biopsies were collected from laboring vaginal and nonlaboring cesarean-section term (37–41 wk) deliveries from healthy pregnancies at sea level and at 3,100 m. After freezing in liquid nitrogen within 5 min of delivery, we quantified hydrophilic and lipid metabolites using 31P and 1H NMR metabolomics. Metabolic markers of oxidative stress, increased glycolysis, and free amino acids were present in placentas following labor at sea level, but not at 3,100 m. In contrast, at 3,100 m, the placentas were characterized by the presence of concentrations of stored energy potential (phosphocreatine), antioxidants, and low free amino acid concentrations. Placentas from pregnancies at sea level subjected to labor display evidence of oxidative stress. However, laboring placentas at 3,100 m have little or no oxidative stress at the time of delivery, suggesting greater resistance to ischemia-reperfusion. We postulate that hypoxic preconditioning might occur in placentas that develop at high altitude. PMID:19864339

Murray, Andrew J.; Beckey, Virginia; Cindrova-Davies, Tereza; Johns, Jemma; Zwerdlinger, Lisa; Jauniaux, Eric; Burton, Graham J.; Serkova, Natalie J.

2010-01-01

201

Mitochondrial reactive oxygen species: A double edged sword in ischemia/reperfusion vs preconditioning  

PubMed Central

Reductions in the blood supply produce considerable injury if the duration of ischemia is prolonged. Paradoxically, restoration of perfusion to ischemic organs can exacerbate tissue damage and extend the size of an evolving infarct. Being highly metabolic organs, the heart and brain are particularly vulnerable to the deleterious effects of ischemia/reperfusion (I/R). While the pathogenetic mechanisms contributing to I/R-induced tissue injury and infarction are multifactorial, the relative importance of each contributing factor remains unclear. However, an emerging body of evidence indicates that the generation of reactive oxygen species (ROS) by mitochondria plays a critical role in damaging cellular components and initiating cell death. In this review, we summarize our current understanding of the mechanisms whereby mitochondrial ROS generation occurs in I/R and contributes to myocardial infarction and stroke. In addition, mitochondrial ROS have been shown to participate in preconditioning by several pharmacologic agents that target potassium channels (e.g., ATP-sensitive potassium (mKATP) channels or large conductance, calcium-activated potassium (mBKCa) channels) to activate cell survival programs that render tissues and organs more resistant to the deleterious effects of I/R. Finally, we review novel therapeutic approaches that selectively target mROS production to reduce postischemic tissue injury, which may prove efficacious in limiting myocardial dysfunction and infarction and abrogating neurocognitive deficits and neuronal cell death in stroke. PMID:24944913

Kalogeris, Theodore; Bao, Yimin; Korthuis, Ronald J.

2014-01-01

202

WAN Internet Protocol IP WAN  

E-print Network

://www.waseda.jp/index.html ftp://ftp.ring.gr.jp/pub/GNU/README 2.5: HTTP FTP URL 2.5 URL 11 WWW TELNET FTP File Transfer Protocol2 1 1 2.1 WWW LAN LAN WAN WAN Internet Protocol IP WAN The Internet1 WWW standard 2 1 The 2Request MTA Message Transfer Agent MTA ISP MUA MTA SMTP Simple Mail Transfer Protocol POP3 Post Office

Kasahara, Hironori

203

Route Optimization in IP Networks  

Microsoft Academic Search

The performance and reliability of the Internet depend, in large part, on the operation of the underlying routing protocols.\\u000a Today’s IP routing protocols compute paths based on the network topology and configuration parameters, without regard to the\\u000a current traffic load on the routers and links. The responsibility for adapting the paths to the prevailing traffic falls to\\u000a the network operators

Jennifer Rexford

204

Mobile IP Conditional Binding Update  

Microsoft Academic Search

Mobile IP protocols use a correspondent registration procedure between a Mobile Node (MN) and its Correspondent Nodes (CNs) to maintain a valid and up-to-date binding association between MN's home address and its current care-of- address whenever a handover occurs. This procedure plays a key role in optimizing the routing path between the two parties by avoiding any kind of dog-leg

Imed Romdhani; Ahmed Yassin Al-Dubai

2007-01-01

205

Wormhole IP over (connectionless) ATM  

Microsoft Academic Search

High-speed switches and routers internally operate using fixed-size cells or segments; variable-size packets are segmented and later reassembled. Connectionless ATM was proposed to quickly carry IP packets segmented into cells (AAL5) using a number of hardware-managed ATM VCs. We show that this is analogous to wormhole routing. We modify this architecture to make it applicable to existing ATM equipment: we

Manolis G. H. Katevenis; Iakovos Mavroidis; Georgios Sapountzis; Evangelia Kalyvianaki; Ioannis Mavroidis; Georgios Glykopoulos

2001-01-01

206

OSI and TCP/IP  

NASA Technical Reports Server (NTRS)

The Open Systems Interconnection Transmission Control Protocol/Internet Protocol (OSI TCP/IP) and the Government Open Systems Interconnection Profile (GOSIP) are compared and described in terms of Federal internetworking. The organization and functions of the Federal Internetworking Requirements Panel (FIRP) are discussed and the panel's conclusions and recommendations with respect to the standards and implementation of the National Information Infrastructure (NII) are presented.

Randolph, Lynwood P.

1994-01-01

207

Preconditioned Krylov subspace methods for solving nonsymmetric matrices from CFD applications  

E-print Network

Preconditioned Krylov subspace methods for solving nonsymmetric matrices from CFD applications Jun arising computational dynamics (CFD) applications. preconditioned iterative methods consist of KrylovCGSTAB, GMRES and TFQMR. Numerical experiments, using several matrices arising various relevant CFD applications

Zhang, Jun

208

Choice of Variables and Preconditioning for Time Dependent Problems  

NASA Technical Reports Server (NTRS)

We consider the use of low speed preconditioning for time dependent problems. These are solved using a dual time step approach. We consider the effect of this dual time step on the parameter of the low speed preconditioning. In addition, we compare the use of two sets of variables, conservation and primitive variables, to solve the system. We show the effect of these choices on both the convergence to a steady state and the accuracy of the numerical solutions for low Mach number steady state and time dependent flows.

Turkel, Eli; Vatsa, Verr N.

2003-01-01

209

Remote preconditioning in normal and hypertrophic rat hearts  

Microsoft Academic Search

Background  The aim of our study was to investigate whether remote preconditioning (RPC) improves myocardial function after ischemia\\/reperfusion\\u000a injury in both normal and hypertrophic isolated rat hearts. This is the first time in world literature that cardioprotection\\u000a by RPC in hypertrophic myocardium is investigated.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Four groups of 7 male Wistar rats each, were used: Normal control, normal preconditioned, hypertrophic control and

Christos Voucharas; Antigoni Lazou; Filippos Triposkiadis; Nikolaos Tsilimingas

2011-01-01

210

The Spacelab IPS Star Simulator  

NASA Technical Reports Server (NTRS)

The cost of doing business in space is very high. If errors occur while in orbit the costs grow and desired scientific data may be corrupted or even lost. The Spacelab Instrument Pointing System (IPS) Star Simulator is a unique test bed that allows star trackers to interface with simulated stars in a laboratory before going into orbit. This hardware-in-the-loop testing of equipment on earth increases the probability of success while in space. The IPS Star Simulator provides three fields of view 2.55 x 2.55 deg each for input into star trackers. The fields of view are produced on three separate monitors. Each monitor has 4096 x 4096 addressable points and can display 50 stars (pixels) maximum at a given time. The pixel refresh rate is 1000 Hz. The spectral output is approximately 550 nm. The available relative visual magnitude range is two to eight visual magnitudes. The star size is less than 100 arcsec. The minimum star movement is less than 5 arcsec and the relative position accuracy is approximately 40 arcsec. The purpose of this paper is to describe the IPS Star Simulator design and to provide an operational scenario so others may gain from the approach and possible use of the system.

Wessling, Francis C., III

1993-01-01

211

Subcortical ischemic cerebrovascular dementia.  

PubMed

It has become increasingly apparent, especially with the advent of MRI brain scanning, that a large number of patients develop signal intensity changes in the subcortical white matter and periventricular region as they age. This appears to be accelerated by risk factors for small vessel cerebrovascular disease such as hypertension, smoking, diabetes mellitus and hyperlipidemia. The major question becomes when such changes become clinically significant. It is obvious that subcortical lacunar-type infarction can be identified by the clinical presentation. For example, typical examples of so-called "lacunar syndrome" include pure motor hemiparesis, pure sensory stroke, sensorimotor stroke, clumsy hand-dysarthria, and hemiataxia-hemiparesis. The issue becomes a measure of impact on functional ability. This is influenced by several factors. Baseline IQ and educational level, as well as expectations of age, certainly play a role. A person who develops cognitive impairment and long tract signs in their 50s or 60s is certainly going to be recognized as more impaired than an 80 year old individual who is retired and primarily is engaged in recreational activity. It would be expected that a person born with limited intellectual capacity and/or limited educational opportunity would be less likely to be identified as impaired than a person who has achieved substantial economic achievement through their innate talents. The concept of tissue loss or lesion load becomes important when determining how pronounced the ischemic cerebrovascular changes translate into functional impairment. Correlative pathology may include cortical atrophy and ventricular dilatation. Loss of either cortical or subcortical tissue function is expected to be related to functional compromise. In addition, there are potential features such as the coexistence of small vessel cerebrovascular disease and Alzheimer's disease. Small vessel cerebrovascular disease might also play a contributing factor in patients susceptible to Dementia with Lewy Bodies or patients susceptible to fronto-temporal dementia or any other dementing process. Thus, the concept of tissue loss or lesion burden of disease becomes increasingly important as we recognize the potential for multifactorial issues, including genetic factors, to contribute to the phenotypic expression. The relationships between cognitive impairment, dementia and subcortical vascular lesions are poorly understood. There have been several papers on the different aspects of cerebral insults and their impact on cognition, the various kinds of dementia and different methods of analyzing the impact of the various insults to the brain. This chapter is an attempt to review all pertinent information currently available on the poorly understood condition of "subcortical ischemic cerebrovascular dementia." PMID:19501711

Menon, Uma; Kelley, Roger E

2009-01-01

212

POPULATION ECOLOGY Population Dynamics of Ips pini and Ips grandicollis in Red Pine  

E-print Network

POPULATION ECOLOGY Population Dynamics of Ips pini and Ips grandicollis in Red Pine Plantations pini (Say) and Ips grandicollis (Eichhoff). The predominant predators obtained were Thanasimus dubius identify factors affecting population densities. The two most common bark beetle species obtained were Ips

Erbilgin, Nadir

213

TCP/IP protocol Possible Attacks TCP/IP protocol Possible Attacks  

E-print Network

TCP/IP protocol Possible Attacks 1 / 20 TCP/IP protocol Possible Attacks By #12; #12; #12 and Network Security Spring Term 2000 #12;TCP/IP protocol Possible Attacks 2 / 20 Table of contents Topic Page # Introduction to TCP/IP protocols 3 Denial of Service Attack Flaw Prevention 6 6 7 Packet Sniffing Attack Flaw

214

Mobile-ip Aeronautical Network Simulation Study  

NASA Technical Reports Server (NTRS)

NASA is interested in applying mobile Internet protocol (mobile-ip) technologies to its space and aeronautics programs. In particular, mobile-ip will play a major role in the Advanced Aeronautic Transportation Technology (AATT), the Weather Information Communication (WINCOMM), and the Small Aircraft Transportation System (SATS) aeronautics programs. This report presents the results of a simulation study of mobile-ip for an aeronautical network. The study was performed to determine the performance of the transmission control protocol (TCP) in a mobile-ip environment and to gain an understanding of how long delays, handoffs, and noisy channels affect mobile-ip performance.

Ivancic, William D.; Tran, Diepchi T.

2001-01-01

215

IP Profiling via Service Cluster Membership Vectors  

SciTech Connect

This study investigates the feasibility of establishing and maintaining a system of compact IP behavioral profiles as a robust means of computer anomaly definition and detection. These profiles are based upon the degree to which a system's (IP's) network traffic is distributed among stable characteristic clusters derived of the aggregate session traffic generated by each of the major network services. In short, an IP's profile represents its degree of membership in these derived service clusters. The goal is to quantify and rank behaviors that are outside of the statistical norm for the services in question, or present significant deviation from profile for individual client IPs. Herein, we establish stable clusters for accessible features of common session traffic, migrate these clusters over time, define IP behavior profiles with respect to these clusters, migrate individual IP profiles over time, and demonstrate the detection of IP behavioral changes in terms of deviation from profile.

Bartoletti, A

2009-02-23

216

Hardware IP Protection during Evaluation Using Embedded Sequential Trojan  

E-print Network

Transfer Level (RTL) descriptions (Soft IP), or gate-level designs directly implementable in hardware (Firm parties without paying the license fee to the IP vendor. To prevent IP piracy, the IP vendors

Bhunia, Swarup

217

Ischemic penumbra in acute stroke: Demonstration by PET with fluorine-18 fluoromisonidazole  

SciTech Connect

Ischemic penumbra (IP) in acute stroke has gained clinical interest since tissue functions may be recovered if perfusion can be reestablished. However, such therapeutic intervention is {open_quotes}blind{close_quotes} since clinical examination can not distinguish IP from developing infarction. In vivo demonstration of IP may have significance for stroke patient management. This study was a preliminary evaluation of detecting IP in vivo by F-18 fluoromisonidazole ([F-18]-FMISO), a hypoxic imaging agent. Static PET imaging was performed after IV injection of 370 MBq of [F-18]-FMISO at 20 and 120 min. Tomograms were reconstructed and evaluated visually in correlation with CT or MR scans. In acute stroke, patients (pts) were called back for the second PET study one month after the initial study. CT was used for confirming infarction. In 6 pts with acute cerebral infarction, three of them had intense [F-18]-FMISO retention in the penumbra surrounding the central, eclipse-like zone of absent radio-activity (infarction) at 2 hr in the acute state, and the penumbra disappeared in association with increased area of infarction on CT in one case in the chronic state. In five pts with chronic infarction, all had no penumbra of [F-18]-FMISO retention. In summary, our preliminary results demonstrate the feasibility of using [F-18]-FMISO PET to detect ischemic penumbra in vivo.

Yeh, S.H.; Liu, R.S.; Hu, H.H. [National Yang-Ming Medical College (Taiwan, Province of China)] [and others

1994-05-01

218

VoIP Secure Communication Protocol satisfying Backward Compatibility  

Microsoft Academic Search

Several VoIP security protocols have been standardized for preventing many VoIP threats. But since several VoIP carriers have different VoIP protocols, end-to-end VoIP secure communication can not be possible. Also when initiator using secure VoIP phone wants a secure communication with responder using non-VoIP phone such as PSTN phone, or cellular phone, etc, so does it. Therefore, we propose VoIP

Joongman Kim; Seokung Yoon; Yoojae Won; Jaeil Lee

2007-01-01

219

PRIMME: PRECONDITIONED ITERATIVE MULTIMETHOD EIGENSOLVE R: METHODS AND SOFTWARE DESCRIPTION  

Microsoft Academic Search

This paper describes the PRIMME software package for the solving large, sparse Hermitian and real symmetric eigenvalue problems. The difficulty and importan ce of these problems have increased over the years, necessitating the use of preconditioning and near optimally converging iterative methods. On the other hand, the complexity of tuning or even using such methods has kept them outside the

ANDREAS STATHOPOULOS; JAMES R. MCCOMBS

220

Parallel Hybrid Sparse Solvers Through Flexible Incomplete Cholesky Preconditioning  

Microsoft Academic Search

Abstract. We consider parallel preconditioning schemes to accelerate the conver- gence of Conjugate Gradients (CG) for sparse linear system solution. We develop methods for constructing and applying preconditioners on multiprocessors using incomplete factorizations with selective inversion for improved,latency-tolerance. We provide empirical results on the efficiency, scalability and quality of our pre- conditioners for sparse matrices from model grids and some

Keita Teranishi; Padma Raghavan

2004-01-01

221

Preconditioned Iterative Solvers for the Generalized Stokes Problem  

E-print Network

and Vivek Sarin Department of Computer Science Texas A&M University College Station, TX 77843 Abstract [1] S. R. Sambavaram and V. Sarin. Preconditioned solenoidal basis method for incompressible fluid Applications, Apr. 2001. [2] V. Sarin. Parallel linear solvers for incompressible fluid problems

222

Ultra-compact preconditioned superprism-based photonic crystal demultiplexers  

Microsoft Academic Search

A preconditioned demultiplexing device is proposed. It based on modifying the behavior of beam during propagation inside the photonic crystal (PC) region. With proper design, the optical beams corresponding to different wavelength channels are spatially separated at their focal plane. Therefore, less area is occupied by each channel, and the total area of the device is considerably reduced. Also, the

B. Momeni; M. Soltani; M. Askari; D. K. Brown; A. Adibi

2005-01-01

223

40 CFR 86.132-00 - Vehicle preconditioning.  

Code of Federal Regulations, 2011 CFR

...highway, US06 or SC03 test cycles. (ii) [Reserved] (iii) If a manufacturer has concerns about fuel effects on adaptive memory systems, a manufacturer may precondition a test vehicle on test fuel and the US06 cycle. Upon request from a...

2011-07-01

224

40 CFR 86.1232-96 - Vehicle preconditioning.  

...Gas-Fueled, Liquefied Petroleum Gas-Fueled and Methanol-Fueled Heavy-Duty Vehicles § 86.1232-96 Vehicle preconditioning...canisters. During this time care must be taken to prevent entry of water or other contaminants into the fuel tank. During...

2014-07-01

225

Implementation of Preconditioned Dual-Time Procedures in OVERFLOW  

Microsoft Academic Search

Preconditioning methods have become the method of choice for the solution of flowfields involving the simultaneous presence of low Mach number flow and transonic flow regions. It is well known that these methods are important for insuring accurate numeri- cal discretization as well as convergence efficiency over various operating conditions such as low Mach num- ber,low Reynolds number and high

Shishir A. Pandya; Sankaran Venkateswaran; Thomas H. Pulliam

2003-01-01

226

A Parallel Implementation of the Block Preconditioned GCR Method  

E-print Network

with GCR. To precondition the GCR method a block Gauss-Jacobi method is used. Approximate solvers are used methods 1 Introduction This paper addresses the parallel implementation of a Krylov accelerated block Gauss-Jacobi method for the DeFT Navier-Stokes solver described in [15], and is the continuation of work

Vuik, Kees

227

40 CFR 86.132-96 - Vehicle preconditioning.  

...after completion of the preconditioning drive. (g) The vehicle shall be soaked...concentration provides at least a 4:1 safety factor against the lean flammability limit...concentration provides at least a 4:1 safety factor against the lean flammability...

2014-07-01

228

Preconditioned Multigrid Simulation of an Axisymmetric Laminar Diffusion Flame \\Lambda  

E-print Network

diffusion flames. We con­ sider a flame sheet problem with one­step chemical reaction. The governingPreconditioned Multigrid Simulation of an Axisymmetric Laminar Diffusion Flame \\Lambda Samir Karaa of an elliptic flame sheet problem. By selecting the generalized minimum residual method as the linear smoother

Zhang, Jun

229

Applying a gaming approach to IP strategy.  

PubMed

Adopting an appropriate IP strategy is an important but complex area, particularly in the pharmaceutical and biotechnology sectors, in which aspects such as regulatory submissions, high competitive activity, and public health and safety information requirements limit the amount of information that can be protected effectively through secrecy. As a result, and considering the existing time limits for patent protection, decisions on how to approach IP in these sectors must be made with knowledge of the options and consequences of IP positioning. Because of the specialized nature of IP, it is necessary to impart knowledge regarding the options and impact of IP to decision-makers, whether at the level of inventors, marketers or strategic business managers. This feature review provides some insight on IP strategy, with a focus on the use of a new 'gaming' approach for transferring the skills and understanding needed to make informed IP-related decisions; the game Patentopolis is discussed as an example of such an approach. Patentopolis involves interactive activities with IP-related business decisions, including the exploitation and enforcement of IP rights, and can be used to gain knowledge on the impact of adopting different IP strategies. PMID:20127561

Gasnier, Arnaud; Vandamme, Luc

2010-02-01

230

The Spacelab IPS Star Simulator  

NASA Technical Reports Server (NTRS)

The cost of doing business in space is very high. If errors occur while in orbit the costs grow and desired scientific data may be corrupted or even lost. The Spacelab Instrument Pointing System (IPS) Star Simulator is a unique test bed that allows star trackers to interface with simulated stars in a laboratory before going into orbit. This hardware-in-the loop testing of equipment on earth increases the probability of success while in space. The IPS Star Simulator provides three fields of view 2.55 x 2.55 degrees each for input into star trackers. The fields of view are produced on three separate monitors. Each monitor has 4096 x 4096 addressable points and can display 50 stars (pixels) maximum at a given time. The pixel refresh rate is 1000 Hz. The spectral output is approximately 550 nm. The available relative visual magnitude range is 2 to 8 visual magnitudes. The star size is less than 100 arc seconds. The minimum star movement is less than 5 arc seconds and the relative position accuracy is approximately 40 arc seconds. The purpose of this paper is to describe the LPS Star Simulator design and to provide an operational scenario so others may gain from the approach and possible use of the system.

Wessling, Francis C., III

1993-01-01

231

Pathophysiologic cascades in ischemic stroke  

PubMed Central

Many advances have been achieved in terms of understanding the molecular and cellular mechanisms of ischemic stroke. But thus far, clinically effective neuroprotectants remain elusive. In this minireview, we summarize the basics of ischemic cascades after stroke, covering neuronal death mechanisms, white matter pathophysiology, and inflammation with an emphasis on microglia. Translating promising mechanistic knowledge into clinically meaningful stroke drugs is very challenging. An integrative approach that encompasses the multimodal and multicell signaling phenomenon of stroke will be required to move forward. PMID:22712739

Xing, Changhong; Arai, Ken; Lo, Eng H.; Hommel, Marc

2013-01-01

232

The Ischemic Stroke Genetics Study (ISGS) Protocol  

Microsoft Academic Search

BACKGROUND: The molecular basis for the genetic risk of ischemic stroke is likely to be multigenic and influenced by environmental factors. Several small case-control studies have suggested associations between ischemic stroke and polymorphisms of genes that code for coagulation cascade proteins and platelet receptors. Our aim is to investigate potential associations between hemostatic gene polymorphisms and ischemic stroke, with particular

James F Meschia; Thomas G Brott; Robert D Brown Jr; Richard JP Crook; Michael Frankel; John Hardy; José G Merino; Stephen S Rich; Scott Silliman; Bradford Burke Worrall

2003-01-01

233

Tolerance to nitroglycerin-induced preconditioning of the endothelium: a human in vivo study.  

PubMed

Damage and dysfunction of the vascular endothelium critically influence clinical outcomes after ischemia and reperfusion (I/R). Brief exposure to organic nitrates can protect the vascular endothelium from I/R injury via a mechanism that is similar to ischemic preconditioning and is independent of hemodynamic changes. The clinical relevance of these protective effects clearly depends on whether they can be sustained over time. Twenty-four healthy (age 25-32) male volunteers were randomized to receive 1) transdermal nitroglycerin (GTN; 0.6 mg/h) administered for 2 h on 1 day only, 2) transdermal GTN for 2 h/day for 7 days, or 3) continuous therapy with transdermal GTN for 7 days. Eight volunteers underwent continuous GTN therapy followed by intra-arterial infusion of the antioxidant vitamin C. Finally, five additional subjects underwent no therapy and served as controls. Endothelial function measurements were performed before and after induction of I/R of the arm. I/R caused a significant blunting of the flow responses to acetylcholine in the control group (P < 0.01 vs. before I/R). A single 2-h GTN dosage, given 24 h before I/R, prevented I/R-induced endothelial dysfunction [P = not significant (NS) vs. before I/R], but this protective effect was completely lost after 1 wk of GTN administration 2 h/day (P < 0.05 vs. before I/R; P = NS vs. control). In subjects who received continuous GTN, endothelial responses were blunted before I/R, and I/R did not cause further endothelial dysfunction. Finally, vitamin C normalized acetylcholine responses and prevented the loss of preconditioning associated with prolonged GTN. In a separate experimental model using isolated human endothelial cells, short-term incubation with GTN caused upregulation of heme oxygenase, an effect that was lost after prolonged GTN administration. Although a single administration of GTN is able to protect the endothelium from I/R-induced endothelial dysfunction, this protection is lost upon prolonged exposure, likely via an oxidative mechanism. PMID:19933412

Gori, Tommaso; Dragoni, Saverio; Di Stolfo, Giuseppe; Sicuro, Silvia; Liuni, Andrew; Luca, Mary Clare; Thomas, George; Oelze, Matthias; Daiber, Andreas; Parker, John D

2010-02-01

234

Analysis of Handoff Mechanisms in Mobile IP  

NASA Astrophysics Data System (ADS)

One of the most important challenges in mobile Internet Protocol (IP) is to provide service for a mobile node to maintain its connectivity to network when it moves from one domain to another. IP is responsible for routing packets across network. The first major version of IP is the Internet Protocol version 4 (IPv4). It is one of the dominant protocols relevant to wireless network. Later a newer version of IP called the IPv6 was proposed. Mobile IPv6 is mainly introduced for the purpose of mobility. Mobility management enables network to locate roaming nodes in order to deliver packets and maintain connections with them when moving into new domains. Handoff occurs when a mobile node moves from one network to another. It is a key factor of mobility because a mobile node can trigger several handoffs during a session. This paper briefly explains on mobile IP and its handoff issues, along with the drawbacks of mobile IP.

Jayaraj, Maria Nadine Simonel; Issac, Biju; Haldar, Manas Kumar

2011-06-01

235

Steganography in Handling Oversized IP Packets  

E-print Network

This paper identifies new class of network steganography methods that utilize mechanisms to handle oversized packets in IP networks: IP fragmentation, PMTUD (Path MTU Discovery) and PLPMTUD (Packetization Layer Path MTU Discovery). In particular, we propose two new steganographic methods and two extensions of existing ones. We show how IP fragmentation simplifies utilizing steganographic methods which requires transmitter-receiver synchronization. We present how mentioned mechanisms can be used to enable hidden communication for both versions of IP protocol: 4 and 6. Also the detection of the proposed methods is enclosed in this paper.

Mazurczyk, Wojciech

2009-01-01

236

Ischemic Renal Disease in Kuwait  

Microsoft Academic Search

Ischemic renal disease (IRD) is a frequent cause of end-stage renal disease. Its prevalence is mainly known from autopsy or retrospective arteriographic studies.This prospective study was conducted in 115 subjects selected from 732 patients with advanced chronic renal failure (CRF). Only patients with clinical features suggestive of IRD were selected for this study. In addition to detailed clinical and laboratory

M. Sheikh; M. R. N. Nampoory; T. Sinan; A. Al-Ali; K. V. Johny

2002-01-01

237

Preconditioning the non-relativistic many-fermion problem  

E-print Network

Preconditioning is at the core of modern many-fermion Monte Carlo algorithms, such as Hybrid Monte Carlo, where the repeated solution of a linear problem involving an ill-conditioned matrix is needed. We report on a performance comparison of three preconditioning strategies, namely Chebyshev polynomials, strong-coupling approximation and weak-coupling expansion. We use conjugate gradient (CG) on the normal equations as well as stabilized biconjugate gradient (BiCGStab) as solvers and focus on the fermion matrix of the unitary Fermi gas. Our results indicate that BiCGStab is by far the most efficient strategy, both in terms of the number of iterations and matrix-vector operations.

Timour Ten; Joaquín E. Drut; Timo A. Lähde

2010-08-21

238

PRECONDITIONING A MIXED DISCONTINUOUS FINITE ELEMENT METHOD FOR RADIATION DIFFUSION  

SciTech Connect

We propose a multilevel preconditioning strategy for the iterative solution of large sparse linear systems arising from a finite element discretization of the radiation diffusion equations. In particular, these equations are solved using a mixed finite element scheme in order to make the discretization discontinuous, which is imposed by the application in which the diffusion equation will be embedded. The essence of the preconditioner is to use a continuous discretization of the original, elliptic diffusion equation for preconditioning the discontinuous equations. We have found that this preconditioner is very effective and makes the iterative solution of the discontinuous diffusion equations practical for large problems. This approach should be applicable to discontinuous discretizations of other elliptic equations. We show how our preconditioner is developed and applied to radiation diffusion problems on unstructured, tetrahedral meshes and show numerical results that illustrate its effectiveness.

JAMES S. WARSA; MICHELE BENZI; TODD A. WAREING; JIM E. MOREL

2002-06-18

239

Mitochondrial ROS production and subsequent ERK phosphorylation are necessary for temperature preconditioning of isolated ventricular myocytes.  

PubMed

Hypothermia and hypothermic preconditioning are known to be profoundly cardioprotective, but the molecular mechanisms of this protection have not been fully explained. In this study, temperature preconditioning (16 °C) was found to be cardioprotective in isolated adult rat ventricular myocytes, enhancing contractile recovery and preventing calcium dysregulation after oxidative stress. Hypothermic preconditioning preserved mitochondrial function by delaying the pathological opening of the mitochondrial permeability transition pore (mPTP), whereas transient mPTP flickering remained unaltered. For the first time, reactive oxygen species (ROS) from the mitochondria are shown to be released exclusively during the hypothermic episodes of the temperature-preconditioning protocol. Using a mitochondrially targeted ROS biosensor, ROS release was shown during the brief bursts to 16 °C of temperature preconditioning. The ROS scavenger N-(2-mercaptopropionyl) glycine attenuated ROS accumulation during temperature preconditioning, abolishing the protective delay in mPTP opening. Temperature preconditioning induces ROS-dependant phosphorylation of the prosurvival kinase extracellular signal-regulated kinase (ERK)1/2. ERK1/2 activation was shown to be downstream of ROS release, as the presence of a ROS scavenger during temperature preconditioning completely blocked ERK1/2 activation. The cardioprotective effects of temperature preconditioning on mPTP opening were completely lost by inhibiting ERK1/2 activation. Thus, mitochondrial ROS release and ERK1/2 activation are both necessary to signal the cardioprotective effects of temperature preconditioning in cardiac myocytes. PMID:22764104

Bhagatte, Y; Lodwick, D; Storey, N

2012-01-01

240

Integrated IP multicast in mobile ad hoc networks with multiple attachments to wired IP networks  

Microsoft Academic Search

Little has been accomplished to-date in bringing together the traditional IP multicast model used in fixed networks and multicast routing protocols for wireless ad hoc networks. We analyse the provision of an integrated IP multicast service in which mobile hosts can seamlessly participate in IP multicast sessions regardless of their point of attachment to the network (e.g. fixed network, ad

Pedro M. Ruiz; Antonio F. Gómez-Skarmeta

2004-01-01

241

Population Genetics of Spruce Bark Beetle Ips typographus (Col., Scolytidae) and Related Ips Species1  

E-print Network

Population Genetics of Spruce Bark Beetle Ips typographus (Col., Scolytidae) and Related Ips method to study population genetic aspects in Ips typographus (L.) be- cause of three highly polymorphic to be regionally different. A genetic basis of these differences was assumed. Seventeen European populations

Standiford, Richard B.

242

Xenon preconditioning reduces brain damage from neonatal asphyxia in rats  

Microsoft Academic Search

Xenon attenuates on-going neuronal injury in both in vitro and in vivo models of hypoxic–ischaemic injury when administered during and after the insult. In the present study, we sought to investigate whether the neuroprotective efficacy of xenon can be observed when administered before an insult, referred to as ‘preconditioning’. In a neuronal–glial cell coculture, preexposure to xenon for 2 h

Daqing Ma; Mahmuda Hossain; Garry K J Pettet; Yan Luo; Ta Lim; Stanislav Akimov; Robert D Sanders; Nicholas P Franks; Mervyn Maze

2006-01-01

243

Local pressure preconditioning method for steady incompressible flows  

Microsoft Academic Search

The convergence and accuracy characteristics of the preconditioned incompressible Euler and Navier–Stokes equations are studied. An object-oriented C++ numerical code has been developed for solving the inviscid and viscous, steady, incompressible flows problems. The code is based on the cell-centred finite volume method. In this scheme, two-dimensional incompressible Euler and Navier–Stokes equations are modified by a robust artificial compressibility (AC)

V. Esfahanian; P. Akbarzadeh

2010-01-01

244

Repetitive hypoxic preconditioning induces an immunosuppressed B cell phenotype during endogenous protection from stroke  

PubMed Central

Background Repetitive hypoxic preconditioning (RHP) creates an anti-inflammatory phenotype that protects from stroke-induced injury for months after a 2-week treatment. The mechanisms underlying long-term tolerance are unknown, though one exposure to hypoxia significantly increased peripheral B cell representation. For this study, we sought to determine if RHP specifically recruited B cells into the protected ischemic hemisphere, and whether RHP could phenotypically alter B cells prior to stroke onset. Methods Adult, male SW/ND4 mice received RHP (nine exposures over 2 weeks; 8 to 11 % O2; 2 to 4 hours) or identical exposures to 21 % O2 as control. Two weeks following RHP, a 60-minute transient middle cerebral artery occlusion was induced. Standard techniques quantified CXCL13 mRNA and protein expression. Two days after stroke, leukocytes were isolated from brain tissue (70:30 discontinuous Percoll gradient) and profiled on a BD-FACS Aria flow cytometer. In a separate cohort without stroke, sorted splenic CD19+ B cells were isolated 2 weeks after RHP and analyzed on an Illumina MouseWG-6 V2 Bead Chip. Final gene pathways were determined using Ingenuity Pathway Analysis. Student’s t-test or one-way analysis of variance determined significance (P?ischemic hemisphere, RHP increased B cell representation by attenuating the diapedesis of monocyte, macrophage, neutrophil and T cells, to quantities indistinguishable from the uninjured, contralateral hemisphere. Pre-stroke splenic B cells isolated from RHP-treated mice had >1,900 genes differentially expressed by microarray analysis. Genes related to B-T cell interactions, including antigen presentation, B cell differentiation and antibody production, were profoundly downregulated. Maturation and activation were arrested in a cohort of B cells from pre-stroke RHP-treated mice while regulatory B cells, a subset implicated in neurovascular protection from stroke, were upregulated. Conclusions Collectively, our data characterize an endogenous neuroprotective phenotype that utilizes adaptive immune mechanisms pre-stroke to protect the brain from injury post-stroke. Future studies to validate the role of B cells in minimizing injury and promoting central nervous system recovery, and to determine whether B cells mediate an adaptive immunity to systemic hypoxia that protects from subsequent stroke, are needed. PMID:24485041

2014-01-01

245

Preconditions for successful guideline implementation: perceptions of oncology nurses  

PubMed Central

Background Although evidence-based guidelines are important for improving the quality of patient care, implementation in practice is below expectations. With the recent focus on team care, guidelines are intended to promote the integration of care across multiple disciplines. We conducted an exploratory study to understand oncology nurses' perceptions of guideline implementation and to learn their views on how their experiences affected the implementation. Methods A qualitative study was used with focus group interviews. We collected data from 11 nurses with more than 5 years of oncology nursing experience in Japan. The data were analyzed using grounded theory. Results Results of the analysis identified "preconditions for successful guideline implementation" as a core category. There were 4 categories (goal congruence, equal partnership, professional self-development and user-friendliness) and 11 subcategories related to organizational, multidisciplinary, individual, and guideline levels. Conclusions Although the guidelines were viewed as important, they were not fully implemented in practice. There are preconditions at the organizational, multidisciplinary, individual, and guideline levels that must be met if an organization is to successfully implement the guideline in clinical settings. Prioritizing strategies by focusing on these preconditions will help to facilitate successful guideline implementation. PMID:22067513

2011-01-01

246

Islet preconditioning via multimodal microfluidic modulation of intermittent hypoxia  

PubMed Central

Simultaneous stimulation of ex vivo pancreatic islets with dynamic oxygen and glucose is a critical technique for studying how hypoxia alters glucose-stimulated response, especially in transplant environments. Standard techniques using a hypoxic chamber cannot provide both oxygen and glucose modulations while monitoring stimulus-secretion coupling factors in real-time. Using novel microfluidic device with integrated glucose and oxygen modulations, we quantified hypoxic impairment of islet response by calcium influx, mitochondrial potentials, and insulin secretion. Glucose-induced calcium response magnitude and phase were suppressed by hypoxia, while mitochondrial hyperpolarization and insulin secretion decreased in coordination. More importantly, hypoxic response was improved by preconditioning islets to intermittent hypoxia (IH, 1min/1min 5%–21% cycling for 1 hour), translating to improved insulin secretion. Moreover, blocking mitochondrial KATP channels removed preconditioning benefits of IH, similar to mechanisms in preconditioned cardiomyocytes. Additionally, the multimodal device can be applied to a variety of dynamic oxygen-metabolic studies in other ex vivo tissues. PMID:22296179

Lo, Joe F.; Wang, Yong; Blake, Alexander; Yu, Gene; Harvat, Tricia A.; Jeon, Hyojin; Oberholzer, Jose; Eddington, David T.

2012-01-01

247

ICS 351: Networking Protocols IP packet forwarding  

E-print Network

) sends a query to a server over a TCP connection the query and response headers are printable ASCII: TCP and UDP network layer: IP, ICMP, ARP data-link layer: Ethernet, WiFi #12;Exactly what happens of protocols, particularly IP, TCP, DNS, and HTTP there are many potential issues on the Internet, with many

Biagioni, Edoardo S.

248

IP over WDM network traffic engineering approaches  

Microsoft Academic Search

The wide spread deployment of DWDM and reconfigurable optical cross-connect equipment gives rise to a new generation of IP over WDM networks. These network combine gigabit and terabit IP routers with WDM switching and transmission systems to create a more flexible and dynamic network. As these networks grow, there is an urgent need to develop and implement new traffic engineering

J. Y. Wei

2002-01-01

249

Mobile IP and virtual private networks  

Microsoft Academic Search

With a growing number of portable computing devices like laptops and personal digital assistants (PDA), the need for seamless connectivity to the global Internet is driving the acceptance of different mobility solutions. Mobile IP is one of the widely accepted mobility solutions for mobile nodes. Though mobile IP caters the seamless connectivity requirements of the mobile nodes, the issues regarding

Ravi Bhagavathula; Nagaraja Thanthry; Ravi Pendse

2002-01-01

250

TCP\\/IP performance over satellite links  

Microsoft Academic Search

Achieving high data rates using TCP\\/IP over satellite networks can be difficult. This article explains some of the reasons TCP\\/IP has difficulty with satellite links. We present solutions to some problems, and describe the state of the research on some the unsolved problems

Craig Partridge; Timothy J. Shepard

1997-01-01

251

Ozone oxidative preconditioning inhibits renal fibrosis induced by ischemia and reperfusion injury in rats  

PubMed Central

Ischemia and reperfusion injury (IRI) is a crucial contributor to the development of renal fibrosis. Ozone has been proposed as a novel medical therapy for various conditions, including organ IRI. The aim of this study was to investigate whether ozone oxidative preconditioning (OzoneOP) has a beneficial effect in preventing the development of renal fibrosis following IRI. Sprague Dawley rats were subjected to 45 min of ischemia followed by 8 weeks of reperfusion. Prior to surgery, rats in the OzoneOP group were treated with ozone and those in the IRI and Sham groups were untreated. Blood samples were collected for the detection of blood urea nitrogen (BUN) and creatinine (Cr) levels. To assess tissue fibrosis, Masson’s trichrome staining was performed. Immunohistochemistry was also performed to determine the localization of ?-smooth muscle actin (?-SMA). Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blotting were conducted to analyze the expression of transforming growth factor (TGF)-?1, ?-SMA and Smad7. The levels of BUN and Cr did not significantly differ between groups. Rats pretreated with ozone showed markedly less interstitial fibrosis than untreated rats following IRI. In addition, immunohistochemistry revealed that ?-SMA expression was attenuated in the OzoneOP group compared with the IRI group. RT-qPCR and western blot analysis showed that OzoneOP inhibited the IRI-induced increases in ?-SMA and TGF-?1 expression levels, and that the IRI-induced reduction in the expression of Smad7 was inhibited in the OzoneOP group. The results indicate that OzoneOP has beneficial effects on ischemic renal fibrosis. OzoneOP may exert its protective effects by a mechanism involving modulation of the TGF-?1/Smad7 pathway. PMID:25371729

WANG, LEI; CHEN, HUI; LIU, XIU-HENG; CHEN, ZHI-YUAN; WENG, XIAO-DONG; QIU, TAO; LIU, LIN; ZHU, HENG-CHENG

2014-01-01

252

Role of uncoupling protein 3 in ischemia-reperfusion injury, arrhythmias, and preconditioning  

PubMed Central

Overexpression of mitochondrial uncoupling proteins (UCPs) attenuates ischemia-reperfusion (I/R) injury in cultured cardiomyocytes. However, it is not known whether UCPs play an essential role in cardioprotection in the intact heart. This study evaluated the cardioprotective efficacy of UCPs against I/R injury and characterized the mechanism of UCP-mediated protection in addition to the role of UCPs in ischemic preconditioning (IPC). Cardiac UCP3 knockout (UCP3?/?) and wild-type (WT) mice hearts were subjected to ex vivo and in vivo models of I/R injury and IPC. Isolated UCP3?/? mouse hearts were retrogradely perfused and found to have poorer recovery of left ventricular function compared with WT hearts under I/R conditions. In vivo occlusion of the left coronary artery resulted in twofold larger infarcts in UCP3?/? mice compared with WT mice. Moreover, the incidence of in vivo I/R arrhythmias was higher in UCP3?/? mice. Myocardial energetics were significantly impaired with I/R, as reflected by a decreased ATP content and an increase in the AMP-to-ATP ratio. UCP3?/? hearts generated more reactive oxygen species (ROS) than WT hearts during I/R. Pretreatment of UCP3?/? hearts with the pharmacological uncoupling agent carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone improved postischemic functional recovery. Also the protective efficacy of IPC was abolished in UCP3?/? mice. We conclude that UCP3 plays a critical role in cardioprotection against I/R injury and the IPC phenomenon. There is increased myocardial vulnerability to I/R injury in hearts lacking UCP3. The mechanisms of UCP3-mediated cardioprotection include regulation of myocardial energetics and ROS generation by UCP3 during I/R. PMID:23457013

Ozcan, Cevher; Palmeri, Monica; Horvath, Tamas L.; Russell, Kerry S.

2013-01-01

253

Space Network IP Services (SNIS): An Architecture for Supporting Low Earth Orbiting IP Satellite Missions  

NASA Technical Reports Server (NTRS)

The NASA Space Network (SN) supports a variety of missions using the Tracking and Data Relay Satellite System (TDRSS), which includes ground stations in White Sands, New Mexico and Guam. A Space Network IP Services (SNIS) architecture is being developed to support future users with requirements for end-to-end Internet Protocol (IP) communications. This architecture will support all IP protocols, including Mobile IP, over TDRSS Single Access, Multiple Access, and Demand Access Radio Frequency (RF) links. This paper will describe this architecture and how it can enable Low Earth Orbiting IP satellite missions.

Israel, David J.

2005-01-01

254

Ischemic acute renal failure and antioxidant therapy in the rat. The relation between glomerular and tubular dysfunction.  

PubMed Central

The effects of antioxidant therapy with probucol were evaluated in rats subjected to 1 h renal ischemia and to 24 h reperfusion. Probucol exerted significant antioxidant effects in renal cortical tubules in vitro when exposed to a catalase-resistant oxidant. At 24 h probucol treatment (IP) improved single nephron glomerular filtration rate (SNGFR) (28.1 +/- 3.3 nl/min) in comparison to untreated ischemic (I) rats (15.2 +/- 3.0), primarily as a result of improving SNGFR in a population of low SNGFR, low flow and/or obstructed nephrons. However, absolute proximal reabsorption remained abnormally low in IP rats at 24 h (5.9 +/- 0.8 nl/min), and cell necrosis was greater than in I rats. Kidney GFR remained low in IP rats due to extensive tubular backleak of inulin measured by microinjection studies. Evaluations after 2 h of reperfusion revealed a higher SNGFR in IP (36 +/- 3.1 nl/min) than I rats (20.8 +/- 2.7 nl/min). Absolute proximal reabsorption was essentially normal (11.6 +/- 1.3 nl/min) in IP rats, which was higher than IP rats at 24 h and the concurrent I rats. Administration of the lipophilic antioxidant, probucol, increased SNGFR and proximal tubular reabsorption within 2 h after ischemic renal failure. Although SNGFR remained higher than I rats at 24 h, absolute reabsorption fell below normal levels and tubular necrosis was more extensive in IP rats. Early improvement in nephron filtration with antioxidants may increase load dependent metabolic demand upon tubules and increase the extent of damage and transport dysfunction. Images PMID:2835399

Bird, J E; Milhoan, K; Wilson, C B; Young, S G; Mundy, C A; Parthasarathy, S; Blantz, R C

1988-01-01

255

Preconditioning improves cardioplegia-related coronary microvascular smooth muscle hypercontractility: Role of KATP channels  

Microsoft Academic Search

Objectives: The effect of preconditioning before hyperkalemic cardioplegia on the coronary smooth muscle remains to be elucidated. We tested the hypothesis that hypoxic preconditioning could protect coronary smooth muscle against subsequent hyperkalemic cardioplegia-induced coronary vasospasm and that this preconditioning effect could be mediated by KATP channels. Methods: Rat coronary arterioles (endothelium-denuded) were studied in a pressurized, no-flow, normothermic state. Simultaneous

Naruto Matsuda; Kathleen G. Morgan; Frank W. Sellke

1999-01-01

256

An Introduction to Voice over the IP: Laboratory Exercise  

NSDL National Science Digital Library

This document provides a sample laboratory exercise which may be used in classes studying Voice over IP. The exercise includes three parts: 1. Configure the classroom network; 2. Simulate VoIP calls; and 3. VoIP Network configuration.

Cherri, Mona

2011-09-19

257

Sulforaphane preconditioning of the Nrf2/HO-1 defense pathway protects the cerebral vasculature against blood-brain barrier disruption and neurological deficits in stroke.  

PubMed

Disruption of the blood-brain barrier (BBB) and cerebral edema are the major pathogenic mechanisms leading to neurological dysfunction and death after ischemic stroke. The brain protects itself against infarction via activation of endogenous antioxidant defense mechanisms, and we here report the first evidence that sulforaphane-mediated preactivation of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream target heme oxygenase-1 (HO-1) in the cerebral vasculature protects the brain against stroke. To induce ischemic stroke, Sprague-Dawley rats were subjected to 70 min middle cerebral artery occlusion (MCAo) followed by 4, 24, or 72 h reperfusion. Nrf2 and HO-1 protein expression was upregulated in cerebral microvessels of peri-infarct regions after 4-72 h, with HO-1 preferentially associated with perivascular astrocytes rather than the cerebrovascular endothelium. In naïve rats, treatment with sulforaphane increased Nrf2 expression in cerebral microvessels after 24h. Upregulation of Nrf2 by sulforaphane treatment prior to transient MCAo (1h) was associated with increased HO-1 expression in perivascular astrocytes in peri-infarct regions and cerebral endothelium in the infarct core. BBB disruption, lesion progression, as analyzed by MRI, and neurological deficits were reduced by sulforaphane pretreatment. As sulforaphane pretreatment led to a moderate increase in peroxynitrite generation, we suggest that hormetic preconditioning underlies sulforaphane-mediated protection against stroke. In conclusion, we propose that pharmacological or dietary interventions aimed to precondition the brain via activation of the Nrf2 defense pathway in the cerebral microvasculature provide a novel therapeutic approach for preventing BBB breakdown and neurological dysfunction in stroke. PMID:24017972

Alfieri, Alessio; Srivastava, Salil; Siow, Richard C M; Cash, Diana; Modo, Michel; Duchen, Michael R; Fraser, Paul A; Williams, Steven C R; Mann, Giovanni E

2013-12-01

258

IPS guidestar selection for stellar mode (ASTRO)  

NASA Technical Reports Server (NTRS)

This report describes how guide stars are selected for the Optical Sensor Package (OSP) for the Instrument Pointing System (IPS) when it is operating in the stellar mode on the ASTRO missions. It also describes how the objective loads are written and how the various roll angles are related; i.e., the celestial roll or position angle, the objective load roll angles, and the IPS gimbal angles. There is a brief description of how the IPS operates and its various modes of operation; i.e., IDOP, IDIN, and OSPCAL.

Mullins, Larry; Wooten, Lewis

1988-01-01

259

Uniform communications software using TCP/IP  

SciTech Connect

Data acquisition applications at Fermilab require a reliable, distributed communication system for downloading, diagnostics, control, and data distribution. TCP/IP over Ethernet was chosen because of its uniform user interface and commercial availability for a number of processors and operating systems. This paper describes the authors software and hardware support for TCP/IP on VAX/VMS, VME/rhoSOS, FASTBUS/rhoSOS, and Unix systems. It includes plans to provide a portable, hardware independent implementation of TCP/IP based on Berkeley BSD software.

Bernett, M.; Oleynik, G. (Fermi National Accelerator Lab., Batavia, IL (USA))

1989-10-01

260

Scalable architecture for VoIP privacy  

NASA Astrophysics Data System (ADS)

An access network for Voice over IP (VoIP) clients (e.g. DOCSIS-based HFC network) often provides a privacy service. However, such a privacy service is limited only to that access network. When VoIP packets are carried over an open IP network or over a network with some connections to the Internet, it is desirable to provide an end-to-end privacy service where each VoIP packet is encrypted at the source and decrypted at the terminating endpoint. Clearly, public key encryption cannot be applied to each voice packet; the performance would be unacceptable regardless of the choice of a public key algorithm. The only alternative is for the two VoIP endpoints to negotiate a shared symmetric key. Since VoIP connections are established only for duration of a phone call, the end-to-end key negotiation needs to occur during each call setup. And it should not noticeably delay the call setup phase. In order to provide end-to-end privacy, it is not sufficient to encrypt all messages between the two endpoints. It is important that the two endpoints authenticate each other - validate each other's identity. Without authentication an adversary might trick two VoIP clients to negotiate keys with her and then sit in the middle of their conversation and record each VoIP packet, before forwarding it to the intended destination. However, direct authentication of the two VoIP endpoints is not always possible in telephony networks - in particular when caller ID blocking services are enabled. To support such anonymity services, it may be sufficient to authenticate not the identity of the caller but the fact that it is a valid subscriber and that all subsequent signaling and voice traffic will be coming from the same source. The PacketCable specifications provide an example of a VoIP architecture with end-to-end privacy that meets the above stated criteria. This paper describes the PacketCable end-to-end privacy approach and suggests additional mechanisms that may be used to further strengthen VoIP privacy under the PacketCable architecture.

Medvinsky, Alexander

2001-07-01

261

Homozygous Prothrombin Gene Mutationand Ischemic Cerebrovascular Disease  

Microsoft Academic Search

We report the case of a 31-year-old woman who, at the age of 26 suffered from an episode of superficial thrombophlebitis in the left leg, experienced two episodes of transient ischemic attacks at the age of 30 and had an ischemic stroke with left-sided hemiparesis at the age of 31 years. A cerebral CT scan showed an ischemic lesion in

Paola Giordano; Domenico De Lucia; Brigida Coppola; Achille Iolascon

1999-01-01

262

Caspase 3 activation is essential for neuroprotection in preconditioning  

Microsoft Academic Search

Sublethal insults can induce tolerance to subsequent stressors in neurons. As cell death activators such as ROS generation and decreased ATP can initiate tolerance, we tested whether other cellular elements normally associated with neuronal injury could add to this process. In an in vivo model of ischemic tolerance, we were surprised to observe widespread caspase 3 cleavage, without cell death,

Bethann McLaughlin; Karen A. Hartnett; Joseph A. Erhardt; Jeffrey J. Legos; Ray F. White; Frank C. Barone; Elias Aizenman

2003-01-01

263

Insulin Preconditioning Elevates p-Akt and Cardiac Contractility after Reperfusion in the Isolated Ischemic Rat Heart  

PubMed Central

Insulin induces cardioprotection partly via an antiapoptotic effect. However, the optimal timing of insulin administration for the best quality cardioprotection remains unclear. We tested the hypothesis that insulin administered prior to ischemia provides better cardioprotection than insulin administration after ischemia. Isolated rat hearts were prepared using Langendorff method and divided into three groups. The Pre-Ins group (Pre-Ins) received 0.5?U/L insulin prior to 15?min no-flow ischemia for 20?min followed by 20?min of reperfusion. The Post-Ins group (Post-Ins) received 0.5?U/L insulin during the reperfusion period only. The control group (Control) was perfused with KH buffer throughout. The maximum of left ventricular derivative of pressure development (dP/dt(max)) was recorded continuously. Measurements of TNF-? and p-Akt in each time point were assayed by ELISA. After reperfusion, dP/dt(max) in Pre-Ins was elevated, compared with Post-Ins at 10 minutes after reperfusion and Control at all-time points. TNF-? levels at 5 minutes after reperfusion in the Pre-Ins were lower than the others. After 5 minutes of reperfusion, p-Akt was elevated in Pre-Ins compared with the other groups. Insulin administration prior to ischemia provides better cardioprotection than insulin administration only at reperfusion. TNF-? suppression is possibly mediated via p-Akt leading to a reduction in contractile myocardial dysfunction. PMID:25197648

Sato, Tamaki; Fukushima, Hisashi; Schricker, Thomas

2014-01-01

264

Weighted graph based ordering techniques for preconditioned conjugate gradient methods  

NASA Technical Reports Server (NTRS)

We describe the basis of a matrix ordering heuristic for improving the incomplete factorization used in preconditioned conjugate gradient techniques applied to anisotropic PDE's. Several new matrix ordering techniques, derived from well-known algorithms in combinatorial graph theory, which attempt to implement this heuristic, are described. These ordering techniques are tested against a number of matrices arising from linear anisotropic PDE's, and compared with other matrix ordering techniques. A variation of RCM is shown to generally improve the quality of incomplete factorization preconditioners.

Clift, Simon S.; Tang, Wei-Pai

1994-01-01

265

Preconditioning methods for ideal and multiphase fluid flows  

NASA Astrophysics Data System (ADS)

The objective of this study is to develop a preconditioning method for ideal and multiphase multispecies compressible fluid flow solver using homogeneous equilibrium mixture model. The mathematical model for fluid flow going through phase change uses density and temperature in the formulation, where the density represents the multiphase mixture density. The change of phase of the fluid is then explicitly determined using the equation of state of the fluid, which only requires temperature and mixture density. The method developed is based on a finite-volume framework in which the numerical fluxes are computed using Roe's approximate Riemann solver and the modified Harten, Lax and Van-leer scheme (HLLC). All speed Roe and HLLC flux based schemes have been developed either by using preconditioning or by directly modifying dissipation to reduce the effect of acoustic speed in its numerical dissipation when Mach number decreases. Preconditioning proposed by Briley, Taylor and Whitfield, Eriksson and Turkel are studied in this research, where as low dissipation schemes proposed by Rieper and Thornber, Mosedale, Drikakis, Youngs and Williams are also considered. Various preconditioners are evaluated in terms of development, performance, accuracy and limitations in simulations at various Mach numbers. A generalized preconditioner is derived which possesses well conditioned eigensystem for multiphase multispecies flow simulations. Validation and verification of the solution procedure are carried out on several small model problems with comparison to experimental, theoretical, and other numerical results. Preconditioning methods are evaluated using three basic geometries; 1) bump in a channel 2) flow over a NACA0012 airfoil and 3) flow over a cylinder, which are then compared with theoretical and numerical results. Multiphase capabilities of the solver are evaluated in cryogenic and non-cryogenic conditions. For cryogenic conditions the solver is evaluated by predicting cavitation on two basic geometries for which experimental data are available, that is, flow over simple foil and a quarter caliber hydrofoil in a tunnel using liquid nitrogen as a fluid. For non-cryogenic conditions, water near boiling conditions is used to predict cavitation on two simple geometries, that is, flow over simple foil in a tunnel and flow over a one caliber ogive. Cavitation predictions in both cryogenic and non-cryogenic cases are shows to agree well with available experimental data.

Gupta, Ashish

266

IP Migration Simplified for Government Professionals  

E-print Network

IP Migration Simplified for Government Professionals Author: Timothy M. O'Neil Corporate, Director and net- work support teams. This SLA defines required bandwidth, packet loss and jitter require- ments

Calyam, Prasad

267

Voice Over IP Curriculum, Option II  

NSDL National Science Digital Library

The Convergence Technology Center has made Voice over IP curriculum available online. This set of curriculum is one of two available on VoIP. The site includes a syllabus and learning activities related to the topic. If you are an educator who would like to gain full access to the complete curriculum, you may email convergence_technology@collin.edu (further instructions for access are available on the site).

2012-10-02

268

Security labeling in TCP/IP networks  

SciTech Connect

TCP/IP is the name commonly used to refer to a suite of networking protocols that was originally developed under the auspices of the Department of Defense for use on the Arpanet. These protocols are in wide use today on a large number of networks and have become accepted as a de facto industry standard. The Transmission Control Protocol (TCP) occupies the transport layer in the protocol suite, and the Internet Protocol (IP) occupies the network layer. In addition, there are a wide variety of other protocols in the DDN protocol suite. For example, the Unreliable Datagram Protocol (UDP) is alternative transport layer protocol that provides a simple unreliable datagram (packet) delivery service and uses the services of IP. The File Transport Protocol (FTP) and TELNET are application layer protocols that provide for file transfers and interactive logins, respectively, across a network using the services of TCP and IP. In this paper, we will discuss security labeling in a TCP/IP network with emphasis on the attempts to standardize labels at the IP layer; however, we will also discuss some of the issues relating to application protocols and privileged server processes in host computer systems. 4 refs., 1 fig.

Brown, C.D.

1989-01-30

269

Recent advances in liver preconditioning: Thyroid hormone, n-3 long-chain polyunsaturated fatty acids and iron  

PubMed Central

Liver preconditioning (PC), defined as an enhanced tolerance to injuring stimuli induced by previous specific maneuvers triggering beneficial functional and molecular changes, is of crucial importance in human liver transplantation and major hepatic resection. For these reasons, numerous PC strategies have been evaluated in experimental models of ischemia-reperfusion liver injury, which have not been transferred to clinical application due to side effects, toxicity and difficulties in implementation, with the exception of the controversial ischemic PC. In recent years, our group has undertaken the assessment of alternate experimental liver PC protocols that might have application in the clinical setting. These include thyroid hormone (T3), n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA), or iron, which suppressed liver damage due to the 1 h ischemia-20 h reperfusion protocol. T3, n-3 LCPUFA and iron are hormetic agents that trigger biologically beneficial effects in the low-dose range, whose multifactorial mechanisms of action are discussed in the work. PMID:22567184

Fernandez, Virginia; Tapia, Gladys; Videla, Luis A

2012-01-01

270

Management of ischemic optic neuropathies  

PubMed Central

Ischemic optic neuropathies (IONs) consist primarily of two types: anterior ischemic optic neuropathy (AION) and posterior ischemic optic neuropathy (PION). AION comprises arteritic AION (A-AION: due to giant cell arteritis) and non-arteritic AION (NA-AION: due to other causes). PION consists of arteritic PION (A-PION: due to giant cell arteritis), non-arteritic PION (NA-PION: due to other causes), and surgical PION (a complication of several systemic surgical procedures). These five types of ION are distinct clinical entities etiologically, pathogenetically, clinically and from the management point of view. In the management of AION, the first crucial step with patients aged 50 and over is to identify immediately whether it is arteritic or not because A-AION is an ophthalmic emergency and requires urgent treatment with high-dose steroid therapy to prevent any further visual loss in one or both eyes. Patients with NA-AION, when treated with systemic corticosteroid therapy within first 2 weeks of onset, had significantly better visual outcome than untreated ones. Systemic risk factors, particularly nocturnal arterial hypotension, play major roles in the development of NA-AION; management of them is essential in its prevention and management. NA-PION patients, when treated with high-dose systemic steroid therapy during the very early stages of the disease, showed significant improvement in visual acuity and visual fields, compared to untreated eyes. A-PION, like A-AION, requires urgent treatment with high-dose steroid therapy to prevent any further visual loss in one or both eyes. There is no satisfactory treatment for surgical PION, except to take prophylactic measures to prevent its development. PMID:21350282

Hayreh, Sohan Singh

2011-01-01

271

Transplantation of hypoxia preconditioned bone marrow mesenchymal stem cells enhances angiogenesis and neurogenesis after cerebral ischemia in rats  

E-print Network

Transplantation of hypoxia preconditioned bone marrow mesenchymal stem cells enhances angiogenesis online 9 March 2012 Keywords: Hypoxic preconditioning Bone marrow mesenchymal stem cell Transplantation for promoting cell survival after transplantation. The present investigation examined the hypothesis

Hayar, Abdallah

272

MSP: A Class of Parallel Multistep Successive Sparse Approximate Inverse Preconditioning Strategies  

Microsoft Academic Search

We develop a class of parallel multistep successive preconditioning strategies to en- hance efficiency and robustness of standard sparse approximate inverse preconditioning techniques. The key idea is to compute a series of simple sparse matrices to approximate the inverse of the original matrix. Studies are conducted to show the advantages of such an approach in terms of both im- proving

Kai Wang; Jun Zhang

2003-01-01

273

Preconditioned Krylov subspace methods for solving nonsymmetric matrices from CFD applications q  

E-print Network

Preconditioned Krylov subspace methods for solving nonsymmetric matrices from CFD applications q dynamics (CFD) applications. The preconditioned iterative methods consist of Krylov subspace accelerators matrices arising from various relevant CFD applications, are reported. Ã? 2000 Elsevier Science S.A. All

Zhang, Jun

274

Effect of heat preconditioning by microwave hyperthermia on human skeletal muscle after eccentric exercise  

Microsoft Academic Search

The purpose of this study was to clarify whether heat precondi- tioning results in less eccentric exercise-induced muscle damage and muscle soreness, and whether the repeated bout effect is enhanced by heat preconditioning prior to eccentric exercise. Nine untrained male volunteers aged 23 ± 3 years participated in this study. Heat preconditioning included treatment with a mi- crowave hyperthermia unit

Norio Saga; Shizuo Katamoto; Hisashi Naito

275

A Preconditioned Newton-Krylov Method for Computing Stationary Pulse Solutions of Mode-locked Lasers  

E-print Network

A Preconditioned Newton-Krylov Method for Computing Stationary Pulse Solutions of Mode-locked laser cavity using a preconditioned matrix-implicit Newton-Krylov solver. Solutions are obtained two solving the periodic boundary value problem for the nonlinear cavity using a Newton-Raphson method

Polz, Martin

276

Sensory Preconditioning in Newborn Rabbits: From Common to Distinct Odor Memories  

ERIC Educational Resources Information Center

This study evaluated whether olfactory preconditioning is functional in newborn rabbits and based on joined or independent memory of odorants. First, after exposure to odorants A+B, the conditioning of A led to high responsiveness to odorant B. Second, responsiveness to B persisted after amnesia of A. Third, preconditioning was also functional…

Coureaud, Gerard; Tourat, Audrey; Ferreira, Guillaume

2013-01-01

277

Relationships between mixis in Brachionus plicatilis and preconditioning of culture medium by crowding  

Microsoft Academic Search

Several experiments with Brachionus plicatilis have been conducted to test the existence of chemical-mediated induction of mixis. In a first experimental set, bioassays were used to test relationships between preconditioning of culture medium to high population density and the occurrence of mixis in mass cultures with these media. The results show that a preconditioned medium has inducing properties that are

Maria José Carmona; Manuel Serra; Maria Rosa Miracle

1993-01-01

278

A Taxonomy of Buffer Overflow Preconditions Matt Bishop, Damien Howard, Sophie Engle, and Sean Whalen  

E-print Network

A Taxonomy of Buffer Overflow Preconditions Matt Bishop, Damien Howard, Sophie Engle, and Sean on vulnerabilities has focused on buffer overflows, in which data exceeding the bounds of an array is loaded of buffer overflow vulnerabilities based upon preconditions, or conditions that must hold for an exploitable

California at Davis, University of

279

Accelerated scaled memoryless BFGS preconditioned conjugate gradient algorithm for unconstrained optimization  

Microsoft Academic Search

An accelerated scaled memoryless BFGS preconditioned conjugate gradient algorithm for solving unconstrained optimization problems is presented. The basic idea is to combine the scaled memoryless BFGS method and the preconditioning technique in the frame of the conjugate gradient method. The preconditioner, which is also a scaled memoryless BFGS matrix, is reset when the Beale-Powell restart criterion holds. The parameter scaling

Neculai Andrei

2010-01-01

280

THE SOLUTION OF LARGE EFIE PROBLEMS VIA PRECONDITIONED MULTILEVEL FAST MULTIPOLE  

E-print Network

THE SOLUTION OF LARGE EFIE PROBLEMS VIA PRECONDITIONED MULTILEVEL FAST MULTIPOLE ALGORITHM T. Malas an effective preconditioning scheme for the iterative solution of the systems formulated by the electric- field the efficiency of the inner-outer solution scheme. We report the solution of large EFIE systems of several

Gürel, Levent

281

Remote ischaemic preconditioning of the hind limb reduces experimental liver warm ischaemia–reperfusion injury  

Microsoft Academic Search

Background: Direct ischaemic preconditioning of the liver reduces ischaemia-reperfusion injury (IRI). Remote ischaemic preconditioning (RIPC) of a limb has been shown to reduce IRI to the heart. This study determined the effect of brief remote ischaemia to the limb in reducing early liver warm IRI. Methods: Twenty-eight male rabbits were allocated into four groups: sham operated, RIPC alone, IRI alone

S. Kanoria; R. Jalan; N. A. Davies; A. M. Seifalian; R. Williams; B. R. Davidson

2006-01-01

282

Robust Parallel Preconditioned Power Grid Simulation on GPU With Adaptive Runtime Performance Modeling and Optimization  

Microsoft Academic Search

Leveraging the power of nowadays graphics process- ing units for robust power grid simulation remains a challenging task. Existing preconditioned iterative methods that require incomplete matrix factorizations cannot be effectively accelerated on graphics processing unit (GPU) due to its limited hardware resource as well as data parallel computing. This paper presents an efficient GPU-based multigrid preconditioning algorithm for robust power

Zhuo Feng; Xueqian Zhao; Zhiyu Zeng

2011-01-01

283

40 CFR 1065.590 - PM sampling media (e.g., filters) preconditioning and tare weighing.  

Code of Federal Regulations, 2012 CFR

... 2012-07-01 false PM sampling media (e.g., filters) preconditioning and...Duty Cycles § 1065.590 PM sampling media (e.g., filters) preconditioning and...the following steps to prepare PM sampling media (e.g., filters) and equipment...

2012-07-01

284

Achyranthes bidentata Polypeptides Reduces Oxidative Stress and Exerts Protective Effects against Myocardial Ischemic/Reperfusion Injury in Rats  

PubMed Central

Achyranthes bidentata, a Chinese medicinal herb, is reported to be neuroprotective. However, its role in cardioprotection remains largely unknown. Our present study aimed to investigate the effects of Achyranthes bidentata polypeptides (ABPP) preconditioning on myocardial ischemia/reperfusion (MI/R) injury and to test the possible mechanisms. Rats were treated with ABPP (10 mg/kg/d, i.p.) or saline once daily for one week. Afterward, all the animals were subjected to 30 min of myocardial ischemia followed by 4 h of reperfusion. ABPP preconditioning for one week significantly improved cardiac function following MI/R. Meanwhile, ABPP reduced infarct size, plasma creatine kinase (CK)/lactate dehydrogenase (LDH) activities and myocardial apoptosis at the end of reperfusion in rat hearts. Moreover, ABPP preconditioning significantly inhibited superoxide generation, gp91phox expression, malonaldialdehyde formation and enhanced superoxide dismutase activity in I/R hearts. Furthermore, ABPP treatment inhibited PTEN expression and increased Akt phosphorylation in I/R rat heart. PI3K inhibitor wortmannin blocked Akt activation, and abolished ABPP-stimulated anti-oxidant effect and cardioprotection. Our study demonstrated for the first time that ABPP reduces oxidative stress and exerts cardioprotection against MI/R injury in rats. Inhibition of PTEN and activation of Akt may contribute to the anti-oxidant capacity and cardioprotection of ABPP. PMID:24084726

Tie, Ru; Ji, Lele; Nan, Ying; Wang, Wenqing; Liang, Xiangyan; Tian, Fei; Xing, Wenjuan; Zhu, Miaozhang; Li, Rong; Zhang, Haifeng

2013-01-01

285

Role of miRs in Cardiac Preconditioning  

PubMed Central

Preconditioning of the heart by sub-lethal ischemia, mild heat shock or hypoxia have evolved as powerful experimental tools to discover novel signaling mechanisms in cardioprotection. The ultimate goal is to determine novel therapeutic targets for potential application in humans in protecting the heart against ischemia-related injuries. In recent years, there has been a tremendous interest in understanding the role of small non-coding RNAs, microRNAs (miRs), in cardiovascular diseases. miRs have been recognized as regulators of gene expression by destabilization and translational inhibition of target mRNAs. Studies have shown that several miRs including miR-1, miR-133, miR-21, miR-126, miR-320, miR-92a and miR-199a are regulated after preconditioning and play an active role in protection of the heart against ischemia/reperfusion injury. These miRs also drive the synthesis of important cardioprotective proteins including HSP-70, eNOS, iNOS, HSP-20, Sirt-1 and HIF-1?. We believe that identification and targeted delivery of miR(s) in the heart could have an immense therapeutic potential in reducing myocardial infarction in patients suffering from heart disease. PMID:20980922

Salloum, Fadi N.; Yin, Chang; Kukreja, Rakesh C.

2014-01-01

286

Physiologically Based Model of Acute Ischemic Stroke  

Microsoft Academic Search

In the treatment of acute ischemic stroke most of the clinical trials have failed, contrasting with promising results in the preclinical stages. This continuing discrepancy suggests some misconceptions in the understanding of acute ischemic stroke. One possible method for identifying the shortcomings of present-day approaches is to integrate all the available knowledge into a single mathematical model and to subject

Vincent Duval; Sylvie Chabaud; Pascal Girard; Michel Cucherat; Marc Hommel; Jean Pierre Boissel

2002-01-01

287

Cerebral ischemic stroke: is gender important?  

PubMed Central

Cerebral stroke continues to be a major cause of death and the leading cause of long-term disability in developed countries. Evidence reviewed here suggests that gender influences various aspects of the clinical spectrum of ischemic stroke, in terms of influencing how a patients present with ischemic stroke through to how they respond to treatment. In addition, this review focuses on discussing the various pathologic mechanisms of ischemic stroke that may differ according to gender and compares how intrinsic and hormonal mechanisms may account for such gender differences. All clinical trials to date investigating putative neuroprotective treatments for ischemic stroke have failed, and it may be that our understanding of the injury cascade initiated after ischemic injury is incomplete. Revealing aspects of the pathophysiological consequences of ischemic stroke that are gender specific may enable gender relevant and effective neuroprotective strategies to be identified. Thus, it is possible to conclude that gender does, in fact, have an important role in ischemic stroke and must be factored into experimental and clinical investigations of ischemic stroke. PMID:23756694

Gibson, Claire L

2013-01-01

288

Chlamydia in Anterior Ischemic Optic Neuropathy  

Microsoft Academic Search

There is an increasing body of evidence linking the common respiratory human pathogen Chlamydia pneumoniae with atherosclerosis and other vascular disorders. Our research was designed to investigate the association of this organism with anterior ischemic optic neuropathy (AION), representing an acute ischemic disorder of the optic nerve head. Sera were examined of 14 consecutive patients with AION and of 14

Pia V. Vécsei; Karl Kircher; Andreas Reitner; Gelas Khanakha; Gerold Stanek

2002-01-01

289

Effect of remote ischemic conditioning on atrial fibrillation and outcome after coronary artery bypass grafting (RICO-trial)  

PubMed Central

Background Pre- and postconditioning describe mechanisms whereby short ischemic periods protect an organ against a longer period of ischemia. Interestingly, short ischemic periods of a limb, in itself harmless, may increase the ischemia tolerance of remote organs, e.g. the heart (remote conditioning, RC). Although several studies have shown reduced biomarker release by RC, a reduction of complications and improvement of patient outcome still has to be demonstrated. Atrial fibrillation (AF) is one of the most common complications after coronary artery bypass graft surgery (CABG), affecting 27-46% of patients. It is associated with increased mortality, adverse cardiovascular events, and prolonged in-hospital stay. We hypothesize that remote ischemic pre- and/or post-conditioning reduce the incidence of AF following CABG, and improve patient outcome. Methods/design This study is a randomized, controlled, patient and investigator blinded multicenter trial. Elective CABG patients are randomized to one of the following four groups: 1) control, 2) remote ischemic preconditioning, 3) remote ischemic postconditioning, or 4) remote ischemic pre- and postconditioning. Remote conditioning is applied at the arm by 3 cycles of 5 minutes of ischemia and reperfusion. Primary endpoint is the incidence AF in the first 72 hours after surgery, detected using a Holter-monitor. Secondary endpoints include length-of-stay on the intensive care unit and in-hospital, and the occurrence of major adverse cardiovascular events at 30 days, 3 months and 1 year. Based on an expected incidence in the control group of 27%, 195 patients per group are needed to detect with 80% power a reduction by 45% following either pre- or postconditioning, while allowing for a 10% dropout and at an alpha of 0.05. With the combined intervention expected to be stronger, we need 75 patients in this group to detect a reduction in incidence of AF of 60%. Discussion The RICO-trial (the effect of Remote Ischemic Conditioning on atrial fibrillation and Outcome) is a randomized controlled multicenter trial, designed to investigate whether remote ischemic pre- and/or post-conditioning of the arm reduce the incidence of AF following CABG surgery. Trial registration ClinicalTrials.gov under NCT01107184. PMID:21605453

2011-01-01

290

Gene expression changes after seizure preconditioning in the three major hippocampal cell layers.  

PubMed

Rodents experience hippocampal damage after status epilepticus (SE) mainly in pyramidal cells while sparing the dentate granule cell layer (DGCL). Hippocampal damage was prevented in rats that had been preconditioned by brief seizures on 2 consecutive days before SE. To identify neuroprotective genes and biochemical pathways changed after preconditioning we compared the effect of preconditioning on gene expression in the CA1 and CA3 pyramidal and DGCLs, harvested by laser capture microscopy. In the DGCL the expression of 632 genes was altered, compared to only 151 and 58 genes in CA1 and CA3 pyramidal cell layers. Most of the differentially expressed genes regulate tissue structure and intra- and extracellular signaling, including neurotransmission. A selective upregulation of energy metabolism transcripts occurred in CA1 pyramidal cells relative to the DGCL. These results reveal a broad transcriptional response of the DGCL to preconditioning, and suggest several mechanisms underlying the neuroprotective effect of preconditioning seizures. PMID:17239605

Borges, Karin; Shaw, Renee; Dingledine, Raymond

2007-04-01

291

Secure Mobile IP Communication Torsten Braun and Marc Danzeisen  

E-print Network

the paper. 5HODWHG :RUN Zao and Condell discuss the use of IPSec over Mobile IP for HA-MN, HA-FA, CN-HA, CN]. IPSec is used to replace IP-IP-tunneling. Adaptations to Mobile IP messages are proposed for coping with IPSec tunnel establishment. Special IPSec tunnel extensions are added to advertisements and registration

Braun, Torsten

292

A Preconditioned Newton-Krylov Method for Computing Steady-State Pulse Solutions of Mode-Locked Lasers  

E-print Network

A Preconditioned Newton-Krylov Method for Computing Steady-State Pulse Solutions of Mode and Optimization Program #12;2 #12;A Preconditioned Newton-Krylov Method for Computing Steady-State Pulse Solutions a specially preconditioned matrix-implicit Newton-Krylov solver. Solutions are obtained at least an order

Polz, Martin

293

Implementation of sparta, a highly parallel circuit simulator by the preconditioned Jacobi method, on a distributed memory machine  

Microsoft Academic Search

This paper investigates an efficient implementation of circuit simulator sparta based on the preconditionedJacobi method on a loosely coupled distributed memory machine Fujitsu AP1000. The preconditioned relaxationmethods are linear solvers effective in large scale circuit simulations. Because the preconditioned Jacobi methodhas a high parallelism, the only problem of parallelization of sparta is the application of the preconditioner to theresidual vector.

Reiji Suda; Yoshio Oyanagi

1995-01-01

294

SNOEREN ET AL.: SINGLEPACKET IP TRACEBACK 1 SinglePacket IP Traceback  

E-print Network

SNOEREN ET AL.: SINGLE­PACKET IP TRACEBACK 1 Single­Packet IP Traceback Alex C. Snoeren, Student to publicly released vulnerability assessment software, to degrade perfor­ mance or even disable vital network services. The consequences are serious and, increasingly, financially disastrous. While dis­ tributed

Snoeren, Alex

295

SNOEREN ET AL.: SINGLE-PACKET IP TRACEBACK 1 Single-Packet IP Traceback  

E-print Network

SNOEREN ET AL.: SINGLE-PACKET IP TRACEBACK 1 Single-Packet IP Traceback Alex C. Snoeren, Student to publicly released vulnerability assessment software, to degrade perfor- mance or even disable vital network services. The consequences are serious and, increasingly, financially disastrous. While dis- tributed

Snoeren, Alex

296

Toward future IP optical backbone networks  

NASA Astrophysics Data System (ADS)

The rapid and aggressive penetration of broadband access services such as fiber to the home (FTTH) has been accelerating the increase in IP traffic volume and new networking technologies are required in order to accommodate future traffic in a cost-effective manner. This paper overviews the advanced IP optical network architecture and technologies for very-large-scale IP backbone networks. These technologies are the key to accommodate the huge volumes of IP traffic expected and control network resources in an effective and dynamic manner. We describe advanced IP optical networking technologies which accommodate multiple service networks using multi-instance technologies, and enable multi-layer traffic engineering using virtual network topology technologies. The migration scenario is described from the existing networks to GMPLS networks; reference is made to the advanced Path Computation Element (PCE) which enables multi-layer traffic engineering and MPLS/GMPLS migration. New network concepts such as Layer 1 Virtual Private Network (L1VPN) and GMPLS interoperability issues, which are being discussed in IETF, are also described.

Urushidani, Shigeo

2005-11-01

297

Routage IP au niveau h^ote Philippe Langevin  

E-print Network

'adresse Algorithme de routage Travaux-Pratiques #12;Mod`ele TCP/IP Le protocole IP (Internet Protocole) constitue la couche r´eseau de TCP/IP. Il g`ere l'adressage et r´ealise l'acheminement des donn´ees. #12;objectif du´eseau programmation r´eseau administration r´eseau parall`elisation #12;Architecture TCP/IP L'architecture TCP/IP

Faccanoni, Gloria

298

Erythropoietin: Powerful protection of ischemic and post-ischemic brain.  

PubMed

Ischemic brain injury inflicted by stroke and cardiac arrest ranks among the leading causes of death and long-term disability in the United States. The brain consumes large amounts of metabolic substrates and oxygen to sustain its energy requirements. Consequently, the brain is exquisitely sensitive to interruptions in its blood supply, and suffers irreversible damage after 10-15?min of severe ischemia. Effective treatments to protect the brain from stroke and cardiac arrest have proven elusive, due to the complexities of the injury cascades ignited by ischemia and reperfusion. Although recombinant tissue plasminogen activator and therapeutic hypothermia have proven efficacious for stroke and cardiac arrest, respectively, these treatments are constrained by narrow therapeutic windows, potentially detrimental side-effects and the limited availability of hypothermia equipment. Mounting evidence demonstrates the cytokine hormone erythropoietin (EPO) to be a powerful neuroprotective agent and a potential adjuvant to established therapies. Classically, EPO originating primarily in the kidneys promotes erythrocyte production by suppressing apoptosis of proerythroid progenitors in bone marrow. However, the brain is capable of producing EPO, and EPO's membrane receptors and signaling components also are expressed in neurons and astrocytes. EPO activates signaling cascades that increase the brain's resistance to ischemia-reperfusion stress by stabilizing mitochondrial membranes, limiting formation of reactive oxygen and nitrogen intermediates, and suppressing pro-inflammatory cytokine production and neutrophil infiltration. Collectively, these mechanisms preserve functional brain tissue and, thus, improve neurocognitive recovery from brain ischemia. This article reviews the mechanisms mediating EPO-induced brain protection, critiques the clinical utility of exogenous EPO to preserve brain threatened by ischemic stroke and cardiac arrest, and discusses the prospects for induction of EPO production within the brain by the intermediary metabolite, pyruvate. PMID:24595981

Nguyen, Anh Q; Cherry, Brandon H; Scott, Gary F; Ryou, Myoung-Gwi; Mallet, Robert T

2014-11-01

299

A survey of IP over ATM architectures  

SciTech Connect

Over the past decade, the Internet has burgeoned into a worldwide information highway consisting of approximately 5 million hosts on over 45,000 interconnected networks. This unprecedented growth, together with the introduction of multimedia workstations, has spurred the development of innovative applications that require high speed, low latency, and real-time transport. Today`s Internet can neither scale in its bandwidth nor guarantee the Quality of Services (QoS) necessary to meet these performance requirements. Many network researchers propose to use the Asynchronous Transfer Mode (ATM) technology as the underlying infrastructure for the next generation of workgroup, campus, and enterprise IP networks. Since ATM is significantly different from today`s legacy network technologies, efficient implementation of IP over ATM is especially challenging. This tutorial paper covers several existing proposals that integrate IP over ATM.

Chen, H.; Tsang, R.; Brandt, J.; Hutchins, J.

1997-07-01

300

Protection of Ischemic Postconditioning against Neuronal Apoptosis Induced by Transient Focal Ischemia Is Associated with Attenuation of NF-?B/p65 Activation  

PubMed Central

Background and Purpose Accumulating evidences have demonstrated that nuclear factor ?B/p65 plays a protective role in the protection of ischemic preconditioning and detrimental role in lethal ischemia-induced programmed cell death including apoptosis and autophagic death. However, its role in the protection of ischemic postconditioning is still unclear. Methods Rat MCAO model was used to produce transient focal ischemia. The procedure of ischemic postconditioning consisted of three cycles of 30 seconds reperfusion/reocclusion of MCA. The volume of cerebral infarction was measured by TTC staining and neuronal apoptosis was detected by TUNEL staining. Western blotting was used to analyze the changes in protein levels of Caspase-3, NF-?B/p65, phosphor- NF-?B/p65, I?B?, phosphor- I?B?, Noxa, Bim and Bax between rats treated with and without ischemic postconditioning. Laser scanning confocal microscopy was used to examine the distribution of NF-?B/p65 and Noxa. Results Ischemic postconditioning made transient focal ischemia-induced infarct volume decrease obviously from 38.6%±5.8% to 23.5%±4.3%, and apoptosis rate reduce significantly from 46.5%±6.2 to 29.6%±5.3% at reperfusion 24 h following 2 h focal cerebral ischemia. Western blotting analysis showed that ischemic postconditioning suppressed markedly the reduction of NF-?B/p65 in cytoplasm, but elevated its content in nucleus either at reperfusion 6 h or 24 h. Moreover, the decrease of I?B? and the increase of phosphorylated I?B? and phosphorylated NF-?B/p65 at indicated reperfusion time were reversed by ischemic postconditioning. Correspondingly, proapoptotic proteins Caspase-3, cleaved Caspase-3, Noxa, Bim and Bax were all mitigated significantly by ischemic postconditioning. Confocal microscopy revealed that ischemic postconditioning not only attenuated ischemia-induced translocation of NF-?B/p65 from neuronal cytoplasm to nucleus, but also inhibited the abnormal expression of proapoptotic protein Noxa within neurons. Conclusions We demonstrated in this study that the protection of ischemic postconditioning on neuronal apoptosis caused by transient focal ischemia is associated with attenuation of the activation of NF-?B/p65 in neurons. PMID:24800741

Liang, Jianmin; Luan, Yongxin; Lu, Bin; Zhang, Hongbo; Luo, Yi-nan; Ge, Pengfei

2014-01-01

301

Ischemic optic neuropathies - where are we now?  

PubMed

Ischemic optic neuropathy is of two types: anterior and posterior. Non-arteritic anterior ischemic optic neuropathy (NA-AION) is the most common type of ischemic optic neuropathy. There are three major misconceptions about NA-AION: (1) that its pathogenesis is not known, (2) that NA-AION and ischemic cerebral stroke are similar in nature, pathogenetically and in management, and (3) that there is no treatment. All these misconceptions are based on lack of in-depth knowledge of the subject. They are discussed in the light of our current scientific knowledge. The pathogenesis of NA-AION is known but is highly complex. NA-AION and ischemic cerebral stroke are very different clinical entities, pathogenetically and in management. Aspirin has no beneficial effect. Corticosteroid therapy during the initial stages can be beneficial. To reduce the risk of development of NA-AION in the other eye or of further visual loss in the same eye, it is essential to reduce as many risk factors as possible. Management of arteritic anterior ischemic optic neuropathy and of posterior ischemic optic neuropathy is discussed. PMID:23821118

Hayreh, Sohan Singh

2013-08-01

302

A simple and efficient preconditioning scheme for heaviside enriched XFEM  

NASA Astrophysics Data System (ADS)

The eXtended Finite Element Method (XFEM) is an approach for solving problems with non-smooth solutions. In the XFEM, the approximate solution is locally enriched to capture discontinuities without requiring a mesh which conforms to the geometric features. One drawback of the XFEM is that an ill-conditioned system of equations results when the ratio of volumes on either side of the interface in an element is small. In this paper, to avoid this ill-conditioning, a simple and efficient scheme based on a geometric preconditioner and constraining degrees of freedom to zero for small intersections is proposed. This geometric preconditioner is computed from the nodal basis functions, and therefore may be constructed prior to building the system of equations. This feature and the low-cost of constructing the preconditioning matrix makes it well suited for nonlinear problems with fixed and moving interfaces.

Lang, Christapher; Makhija, David; Doostan, Alireza; Maute, Kurt

2014-11-01

303

Aerodynamic shape optimization using preconditioned conjugate gradient methods  

NASA Technical Reports Server (NTRS)

In an effort to further improve upon the latest advancements made in aerodynamic shape optimization procedures, a systematic study is performed to examine several current solution methodologies as applied to various aspects of the optimization procedure. It is demonstrated that preconditioned conjugate gradient-like methodologies dramatically decrease the computational efforts required for such procedures. The design problem investigated is the shape optimization of the upper and lower surfaces of an initially symmetric (NACA-012) airfoil in inviscid transonic flow and at zero degree angle-of-attack. The complete surface shape is represented using a Bezier-Bernstein polynomial. The present optimization method then automatically obtains supercritical airfoil shapes over a variety of freestream Mach numbers. Furthermore, the best optimization strategy examined resulted in a factor of 8 decrease in computational time as well as a factor of 4 decrease in memory over the most efficient strategies in current use.

Burgreen, Greg W.; Baysal, Oktay

1993-01-01

304

Space-Based Voice over IP Networks  

NASA Technical Reports Server (NTRS)

In human space exploration missions (e.g. a return to the Moon and for future missions to Mars), there will be a need to provide voice communications services. In this work we focus on the performance of Voice over IP (VoIP) techniques applied to space networks, where long range latencies, simplex links, and significant bit error rates occur. Link layer and network layer overhead issues are examined. Finally, we provide some discussion on issues related to voice conferencing in the space network environment.

Nguyen, Sam P.; Okino, Clayton; Walsh, William; Clare, Loren

2007-01-01

305

Towards more power efficient IP lookup engines  

E-print Network

?xes into 32 bit entries. The expanded entries are then used as memory location to store the nexthop corresponding to that pre?x. This transforms the IP lookup operation into a single memory access. However this approach may not be scalable for IPv 6 addresses...?xes into 32 bit entries. The expanded entries are then used as memory location to store the nexthop corresponding to that pre?x. This transforms the IP lookup operation into a single memory access. However this approach may not be scalable for IPv 6 addresses...

Ahmad, Seraj

2007-04-25

306

Preconditioned iterative methods for inhomogeneous acoustic scattering applications  

NASA Astrophysics Data System (ADS)

This thesis develops and analyzes efficient iterative methods for solving discretizations of the Lippmann--Schwinger integral equation for inhomogeneous acoustic scattering. Analysis and numerical illustrations of the spectral properties of the scattering problem demonstrate that a significant portion of the spectrum is approximated well on coarse grids. To exploit this, I develop a novel restarted GMRES method with adaptive deflation preconditioning based on spectral approximations on multiple grids. Much of the literature in this field is based on exact deflation, which is not feasible for most practical computations. This thesis provides an analytical framework for general approximate deflation methods and suggests a way to rigorously study a host of inexactly-applied preconditioners. Approximate deflation algorithms are implemented for scattering through thin inhomogeneities in photonic band gap problems. I also develop a short term recurrence for solving the one dimensional version of the problem that exploits the observation that the integral operator is a low rank perturbation of a self-adjoint operator. This method is based on strategies for solving Schur complement problems, and provides an alternative to a recent short term recurrence algorithm for matrices with such structure that we show to be numerically unstable for this application. The restarted GMRES method with adaptive deflation preconditioning over multiple grids, as well as the short term recurrence method for operators with low rank skew-adjoint parts, are very effective for reducing both the computational time and computer memory required to solve acoustic scattering problems. Furthermore, the methods are sufficiently general to be applicable to a wide class of problems.

Sifuentes, Josef

307

The effects of specific preconditioning activities on acute sprint performance.  

PubMed

Previous research suggests that specific preconditioning activities such as whole-body vibration (WBV) and resistance training may play an important role in ensuing dynamic activities. The purpose of this study was to examine the effects of 2 preconditioning activities, WBV and power cleans (PC), on acute sprint performance. Two studies were conducted in which 14 (WBV) and 9 (PC) male track and field athletes were subjects. The WBV treatment consisted of 4 bouts of 5 seconds of high-knee running on a vibrating platform at 0, 30, 40, or 50 Hz. The PC treatment consisted of 3 PC reps at 90% 1RM. In both cases, acute sprint performance was the dependent variable of interest. For WBV, split times were recorded at 10, 20, and 40 m. Reaction times (RXN) as well as 5-, 10-, and 40-m split times were recorded for the PC study. Results indicated no significant differences between treatment and nontreatment groups for both studies. However, significant correlations were present between RXN and 5-m splits (r = 0.65) and RXN and 10-m splits (r = 0.63), although they decreased as a function of sprint distance to r = 0.43 at 40 m. These results suggest little efficacy for the use of WBV and PC as a means of augmenting acute sprint performance. However, a trend within the 30-Hz protocol may suggest that WBV as part of a warm-up for sprinting activities greater than 40 m (i.e., 100 m) could potentially result in a decreased sprint time of nearly 1/10th of a second, which is worth future consideration. PMID:19528862

Guggenheimer, Joshua D; Dickin, D Clark; Reyes, Gabriel F; Dolny, Dennis G

2009-07-01

308

Secure file transfer over TCP\\/IP  

Microsoft Academic Search

With the spread of internetworks able to link LANs, and the availability of network hardware to monitor network traffic, the need to add additional security to traditional network utilities is becoming imperative. The development of security extensions to the FTP file transfer utility\\/protocol in the TCP\\/IP communications suite in order to provide authentication of the user and encryption of the

Lawrie BROWN; M. G. Il Jaatun

1992-01-01

309

ICS 351: Networking Protocols IP packet forwarding  

E-print Network

: HTTP a client (browser) sends a query to a server over a TCP connection, the server responds by the server, immediately or after a given time (e.g. 5min) #12;12 Networking Protocols: TCP TCP provides layer: TCP and UDP network layer: IP, ICMP, ARP data-link layer: Ethernet, WiFi #12;2 What happens

Biagioni, Edoardo S.

310

Ips Engraver Beetles (Coleoptera: Curculionidae: Scolytinae)1  

Microsoft Academic Search

INTRODUCTION: Pine bark beetles are frequent pests of stressed pines ( Pinus spp.) in the southern United States. The five most common southern pine bark beetle species include three in the genus Ips (the six-spined engraver, I. calligraphus (Germar); the southern pine engraver, I. grandicollis (Eichhoff); and the small southern pine engraver, I. avulsus (Eichhoff)) (Fig. 1), and two species

Jeffrey M. Eickwort; Albert E. Mayfield III; John L. Foltz

311

IP routing processing with graphic processors  

Microsoft Academic Search

Throughput and programmability have always been the central, but generally conflicting concerns for modern IP router designs. Current high performance routers depend on proprietary hardware solutions, which make it difficult to adapt to ever-changing network protocols. On the other hand, software routers offer the best flexibility and programmability, but could only achieve a throughput one order of magnitude lower. Modern

Shuai Mu; Xinya Zhang; Nairen Zhang; Jiaxin Lu; Yangdong Steve Deng; Shu Zhang

2010-01-01

312

Call progress time measurement in IP telephony  

NASA Astrophysics Data System (ADS)

Usually a voice call is established through multiple stages in IP telephony. In the first stage, a phone number is dialed to reach a near-end or call-originating IP-telephony gateway. The next stages involve user identification through delivering an m-digit user-id to the authentication and/or billing server, and then user authentication by using an n- digit PIN. After that, the caller is allowed (last stage dial tone is provided) to dial a destination phone number provided that authentication is successful. In this paper, we present a very flexible method for measuring call progress time in IP telephony. The proposed technique can be used to measure the system response time at every stage. It is flexible, so that it can be easily modified to include new `tone' or a set of tones, or `voice begin' can be used in every stage to detect the system's response. The proposed method has been implemented using scripts written in Hammer visual basic language for testing with a few commercially available IP telephony gateways.

Khasnabish, Bhumip

1999-11-01

313

Scalable IP Lookup for Programmable Routers  

Microsoft Academic Search

Continuing growth in optical link speeds places in- creasing demands on the performance of Internet routers, while deployment of embedded and distributed network services im- poses new demands for flexibility and programmability. IP ad- dress lookup has become a significant performance bottleneck for the highest performance routers. Amid the vast array of aca- demic and commercial solutions to the problem,

David E. Taylor; John W. Lockwood; Todd S. Sproull; Jonathan S. Turner; David B. Parlour

2002-01-01

314

Adaptive Modelling of IP Packet Aggregation  

Microsoft Academic Search

DiffServ is characterised as an aggregation of flows where packets are classified into behaviour aggregates identified by the DS field in the IP header. Packets are then queued and forwarded based on their source and destination addresses and the DS field value. Modelling this aggregation adaptively would enable guaranteeing the QoS for the class of traffic the aggregation carries. A

Abbas Makki

315

An introduction to IP multicast traffic engineering  

Microsoft Academic Search

In this paper, we discuss the use of IP traffic engineering (TE) capabilities for the deployment and the maintenance of multicast distribution trees along paths that will comply with specific quality of service (QoS) requirements, expressed by parameters like the loss rate or the interpacket delay variation. Such parameters aim at reflecting the level of quality associated to the. provisioning

Christian JACQUENET; Christophe PROUST

2002-01-01

316

Practical Data Hiding in TCP\\/IP  

Microsoft Academic Search

This work relates the areas of steganography, network protocols and security for practical data hiding in communication networks employing TCP\\/IP. Two approaches are proposed based on packet header manipulation and packet ordering within the IPSec framework. For the former the Internet protocol IPv4 header is analyzed to identify covert channels by exploiting redundancy and multiple interpretations of protocol strategies; by

Kamran Ahsan; Deepa Kundur

2002-01-01

317

Operational Space Weather Products at IPS  

NASA Astrophysics Data System (ADS)

IPS Radio and Space Services operates an extensive network (IPSNET) of monitoring stations and observatories within the Australasian and Antarctic regions to gather information on the space environment. This includes ionosondes, magnetometers, GPS-ISM, oblique HF sounding, riometers, and solar radio and optical telescopes. IPS exchanges this information with similar organisations world-wide. The Regional Warning Centre (RWC) is the Australian Space Forecast Centre (ASFC) and it utilizes this data to provide products and services to support customer operations. A wide range of customers use IPS services including; defence force and emergency services using HF radio communications and surveillance systems, organisations involved in geophysical exploration and pipeline cathodic protection, GPS users in aviation. Subscriptions to the alerts, warnings, forecasts and reports regarding the solar, geophysical and ionospheric conditions are distributed by email and Special Message Service (SMS). IPS also develops and markets widely used PC software prediction tools for HF radio skywave and surface wave (ASAPS/GWPS) and provides consultancy services for system planning.

Neudegg, D.; Steward, G.; Marshall, R.; Terkildsen, M.; Kennewell, J.; Patterson, G.; Panwar, R.

2008-12-01

318

Neuroprotective Mechanisms of Taurine against Ischemic Stroke  

PubMed Central

Ischemic stroke exhibits a multiplicity of pathophysiological mechanisms. To address the diverse pathophysiological mechanisms observed in ischemic stroke investigators seek to find therapeutic strategies that are multifaceted in their action by either investigating multipotential compounds or by using a combination of compounds. Taurine, an endogenous amino acid, exhibits a plethora of physiological functions. It exhibits antioxidative properties, stabilizes membrane, functions as an osmoregulator, modulates ionic movements, reduces the level of pro-inflammators, regulates intracellular calcium concentration; all of which contributes to its neuroprotective effect. Data are accumulating that show the neuroprotective mechanisms of taurine against stroke pathophysiology. In this review, we describe the neuroprotective mechanisms employed by taurine against ischemic stroke and its use in clinical trial for ischemic stroke. PMID:24961429

Menzie, Janet; Prentice, Howard; Wu, Jang-Yen

2013-01-01

319

Diagnosis and management of ischemic colitis  

Microsoft Academic Search

The clinical presentation and outcome of ischemic colitis has a wide spectrum. Impaired perfusion of blood to the bowel from\\u000a a variety of causes is the underlying pathophysiology. The presence of diarrhea, abdominal pain, and mild lower gastrointestinal\\u000a bleeding should prompt consideration of ischemic colitis as a cause. Although many laboratory tests and radiographic images\\u000a may suggest the diagnosis, endoscopic

Jayaprakash Sreenarasimhaiah

2005-01-01

320

Diagnosis and Management of Ischemic Stroke  

Microsoft Academic Search

\\u000a Until relatively recently, ischemic stroke management was a classic example of “diagnose and adios.” Care of patients presenting\\u000a to the hospital or clinic with symptoms of stroke consisted of aspirin followed by rehabilitation, with few disease-specific\\u000a strategies directed toward optimal treatment and outcomes. The past two decades have witnessed an explosion of research into\\u000a ischemic stroke. We now have specific

Aslam M. Khaja

321

Docosahexaenoic Acid Therapy of Experimental Ischemic Stroke  

Microsoft Academic Search

We examined the neuroprotective efficacy of docosahexaenoic acid (DHA), an omega-3 essential fatty acid family member, in\\u000a acute ischemic stroke; studied the therapeutic window; and investigated whether DHA administration after an ischemic stroke\\u000a is able to salvage the penumbra. In each series described below, SD rats underwent 2 h of middle cerebral artery occlusion\\u000a (MCAo). In series 1, DHA or saline

Ludmila Belayev; Larissa Khoutorova; Kristal D. Atkins; Tiffany N. Eady; Song Hong; Yan Lu; Andre Obenaus; Nicolas G. Bazan

2011-01-01

322

Simulation of electrophoretic stretching of DNA in a microcontraction using an obstacle array for conformational preconditioning  

E-print Network

Recently our group has reported experiments using an obstacle array to precondition the conformations of DNA molecules to facilitate their stretch in a microcontraction. Based upon previous successes simulating electrophoretic ...

Doyle, Patrick S.

323

Hybrid preconditioning for iterative diagonalization of ill-conditioned generalized eigenvalue problems in electronic structure calculations  

NASA Astrophysics Data System (ADS)

The iterative diagonalization of a sequence of large ill-conditioned generalized eigenvalue problems is a computational bottleneck in quantum mechanical methods employing a nonorthogonal basis for ab initio electronic structure calculations. We propose a hybrid preconditioning scheme to effectively combine global and locally accelerated preconditioners for rapid iterative diagonalization of such eigenvalue problems. In partition-of-unity finite-element (PUFE) pseudopotential density-functional calculations, employing a nonorthogonal basis, we show that the hybrid preconditioned block steepest descent method is a cost-effective eigensolver, outperforming current state-of-the-art global preconditioning schemes, and comparably efficient for the ill-conditioned generalized eigenvalue problems produced by PUFE as the locally optimal block preconditioned conjugate-gradient method for the well-conditioned standard eigenvalue problems produced by planewave methods.

Cai, Yunfeng; Bai, Zhaojun; Pask, John E.; Sukumar, N.

2013-12-01

324

Block Locally Optimal Preconditioned Eigenvalue Xolvers (BLOPEX) in hypre and PETSc  

Microsoft Academic Search

We describe our software package Block Locally Optimal Preconditioned Eigenvalue Xolvers (BLOPEX) publicly released recently. BLOPEX is available as a stand-alone serial library, as an external package to PETSc (\\

A. V. Knyazev; M. E. Argentati; I. Lashuk; E. E. Ovtchinnikov

2007-01-01

325

Preconditioning for Numerical Simulation of Low Mach Number Three-Dimensional Viscous Turbomachinery Flows  

NASA Technical Reports Server (NTRS)

A preconditioning scheme has been implemented into a three-dimensional viscous computational fluid dynamics code for turbomachine blade rows. The preconditioning allows the code, originally developed for simulating compressible flow fields, to be applied to nearly-incompressible, low Mach number flows. A brief description is given of the compressible Navier-Stokes equations for a rotating coordinate system, along with the preconditioning method employed. Details about the conservative formulation of artificial dissipation are provided, and different artificial dissipation schemes are discussed and compared. The preconditioned code was applied to a well-documented case involving the NASA large low-speed centrifugal compressor for which detailed experimental data are available for comparison. Performance and flow field data are compared for the near-design operating point of the compressor, with generally good agreement between computation and experiment. Further, significant differences between computational results for the different numerical implementations, revealing different levels of solution accuracy, are discussed.

Tweedt, Daniel L.; Chima, Rodrick V.; Turkel, Eli

1997-01-01

326

Hybrid preconditioning for iterative diagonalization of ill-conditioned generalized eigenvalue problems in electronic structure calculations  

SciTech Connect

The iterative diagonalization of a sequence of large ill-conditioned generalized eigenvalue problems is a computational bottleneck in quantum mechanical methods employing a nonorthogonal basis for ab initio electronic structure calculations. We propose a hybrid preconditioning scheme to effectively combine global and locally accelerated preconditioners for rapid iterative diagonalization of such eigenvalue problems. In partition-of-unity finite-element (PUFE) pseudopotential density-functional calculations, employing a nonorthogonal basis, we show that the hybrid preconditioned block steepest descent method is a cost-effective eigensolver, outperforming current state-of-the-art global preconditioning schemes, and comparably efficient for the ill-conditioned generalized eigenvalue problems produced by PUFE as the locally optimal block preconditioned conjugate-gradient method for the well-conditioned standard eigenvalue problems produced by planewave methods.

Cai, Yunfeng, E-mail: yfcai@math.pku.edu.cn [LMAM and School of Mathematical Sciences, Peking University, Beijing 100871 (China) [LMAM and School of Mathematical Sciences, Peking University, Beijing 100871 (China); Department of Computer Science, University of California, Davis 95616 (United States); Bai, Zhaojun, E-mail: bai@cs.ucdavis.edu [Department of Computer Science and Department of Mathematics, University of California, Davis 95616 (United States)] [Department of Computer Science and Department of Mathematics, University of California, Davis 95616 (United States); Pask, John E., E-mail: pask1@llnl.gov [Condensed Matter and Materials Division, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Sukumar, N., E-mail: nsukumar@ucdavis.edu [Department of Civil and Environmental Engineering, University of California, Davis 95616 (United States)

2013-12-15

327

IP over P2P: enabling self-configuring virtual IP networks for grid computing  

Microsoft Academic Search

Peer-to-peer (P2P) networks have mostly fo- cused on task oriented networking, where networks are constructed for single applications, i.e. file-sharing, DNS caching, etc. In this work, we introduce IPOP, a system for creating virtual IP networks on top of a P2P overlay. IPOP enables seamless access to Grid resources spanning multiple domains by aggregating them into a virtual IP network

Arijit Ganguly; Abhishek Agrawal; P. Oscar Boykin; Renato J. O. Figueiredo

2006-01-01

328

Trapeze\\/IP: TCP\\/IP at Near-Gigabit Speeds  

Microsoft Academic Search

This paper presents experiences with high-speed TCP\\/IP networking on a gigabit-per-second Myrinet network, using a Myrinet messaging system called Trapeze. We explore the effects of common optimizations above and below the TCP\\/IP protocol stack, including zero-copy sockets, large packets with scatter\\/gather I\\/O, checksum offloading, message pipelining, and interrupt suppres- sion. Our experiments use extended FreeBSD 4.0 ker- nels on a

Andrew J. Gallatin; Jeffrey S. Chase; Ken Yocum

1999-01-01

329

Secure Voice over IP conferencing with decentralized group encryption  

E-print Network

This thesis addresses the development of an end-to-end secure Voice over IP (VoIP) conference system. We are particularly interested in challenges associated with deploying such a system in ad-hoc networks containing low ...

Kannan, Steven (Steven K.)

2007-01-01

330

Modeling and assessing secure Voice over IP performance  

E-print Network

Voice over Internet Protocol (VoIP) systems enable efficient communications over data networks, but security of VoIP and the impact of that security on communications quality has not been quantitatively modeled. A ...

Zue, Cory L

2005-01-01

331

Optimization of OSPF Routing in IP Networks  

NASA Astrophysics Data System (ADS)

The Internet is a huge world-wide packet switching network comprised of more than 13,000 distinct subnetworks, referred to as Autonomous Systems (ASs) autonomous system AS . They all rely on the Internet Protocol (IP) internet protocol IP for transport of packets across the network. And most of them use shortest path routing protocols shortest path routing!protocols , such as OSPF or IS-IS, to control the routing of IP packets routing!of IP packets within an AS. The idea of the routing is extremely simple — every packet is forwarded on IP links along the shortest route between its source and destination nodes of the AS. The AS network administrator can manage the routing of packets in the AS by supplying the so-called administrative weights of IP links, which specify the link lengths that are used by the routing protocols for their shortest path computations. The main advantage of the shortest path routing policy is its simplicity, allowing for little administrative overhead. From the network engineering perspective, however, shortest path routing can pose problems in achieving satisfactory traffic handling efficiency. As all routing paths depend on the same routing metric routing!metric , it is not possible to configure the routing paths for the communication demands between different pairs of nodes explicitly or individually; the routing can be controlled only indirectly and only as a whole by modifying the routing metric. Thus, one of the main tasks when planning such networks is to find administrative link weights that induce a globally efficient traffic routing traffic!routing configuration of an AS. It turns out that this task leads to very difficult mathematical optimization problems. In this chapter, we discuss and describe exact integer programming models and solution approaches as well as practically efficient smart heuristics for such shortest path routing problems shortest path routing!problems .

Bley, Andreas; Fortz, Bernard; Gourdin, Eric; Holmberg, Kaj; Klopfenstein, Olivier; Pióro, Micha?; Tomaszewski, Artur; Ümit, Hakan

332

Differentiation of ischemic from non-ischemic central retinal vein occlusion during the early acute phase  

Microsoft Academic Search

We investigated prospectively in 128 patients (140 eyes) the role of six routine clinical tests in the differentiation of ischemic central retinal vein occlusion (CRVO) from non-ischemic CRVO during its early acute phase. There were fourfunctional tests [visual acuity, visual fields, relative afferent pupillary defect (RAPID), electroretinography (ERG)] and twomorphologic tests (ophthalmoscopy and fluorescein fundus angiography). We found that none

Sohan Singh Hayreh; Marie R. Klugman; Meena Beri; Alan E. Kimura; Patricia Podhajsky

1990-01-01

333

Atorvastatin preconditioning improves the forward blood flow in the no-reflow rats.  

PubMed

Atorvastatin is not only an antilipemic but also used as an anti-inflammatory medicine in heart disease. Our working hypothesis was that atorvastatin preconditioning could improve the forward blood flow in the no-reflow rats associated with inflammation. We investigated that two doses of atorvastatin preconditioning (20 and 5 mg/kg/day) could alleviate deterioration of early cardiac diastolic function in rats with inflammation detected by echocardiography and haemodynamics. This benefit was obtained from the effect of atorvastatin preconditioning on improving forward blood flow and preserving the infarct cardiomyocytes, which was estimated by Thioflavin S and TTC staining in rats with myocardial ischemia/reperfusion. Subsequently, the improving of forward blood flow was ascribed to reduction of microthrombus in microvascular and myocardial fibrosis observed by MSB and Masson's trichrome staining with atorvastatin preconditioning. Ultimately, we found that atorvastatin preconditioning could reduce inflammation factor, such as tumor necrosis factor-? and fibrinogen-like protein 2, both in myocardial and in mononuclear cells, which probably attribute to microcirculation dysfunction in no-reflow rats detected by immunohistochemistry staining, western blot, and ELISA detection, respectively. In conclusion, atorvastatin preconditioning could alleviate deterioration of early cardiac diastolic function and improve the forward blood flow in the no-reflow rats attributing to reduction of TNF-? and fgl-2 expression. PMID:22985249

Shao, Liang; Zhang, Yong; Ma, Aiqun; Zhang, Ping; Wu, Dayin; Li, Wenzhu; Wang, Jue; Liu, Kun; Wang, Zhaohui

2014-02-01

334

High Performance IP Routing Table Lookup using CPU Caching  

Microsoft Academic Search

Wire-speed IP (Internet Protocol) routers require very fast routing table lookup for incoming IP packets. The routing table lookup operation is time consuming because the part of an IP address used in the lookup, i.e., the network address portion, is variable in length. This paper describes the routing table lookup algorithm used in a cluster-based paral- lel IP router project

Tzi-cker Chiueh; Prashant Pradhan

1999-01-01

335

IP- -: A Reduced Internet Protocol for Optical Packet Networking  

NASA Astrophysics Data System (ADS)

IP- - is proposed as an Internet Protocol suitable for optical packet networking. As optical routers require much faster control than electric ones and lack of optical buffers other than those by fiber delay lines requires fixed time control, Internet Protocols must be at least as simple as IPv4 and much simpler than IPv6. IP- - also addresses issues of IP address space exhaustion and IP routing table explosion.

Ohta, Masataka; Fujikawa, Kenji

336

Role of ipsdienol, ipsenol, and cis-verbenol in chemical ecology of Ips avulsus, Ips calligraphus, and Ips grandicollis (Coleoptera: Curculionidae: Scolytinae).  

PubMed

Stressed or damaged pine (Pinus sp.) trees in the southeastern United States are often colonized simultaneously by three southern Ips species (Coleoptera: Curculionidae: Scolytinae): small southern pine engraver, Ips avulsus (Eichhoff); sixspined ips, Ips calligraphus (Germar); and eastern fivespined ips, Ips grandicollis (Eichhoff). All three species mediate colonization of host material with volatile pheromones. All of the southern Ips produce cis-verbenol, and either ipsdienol or ipsenol, and electrophysiological studies have demonstrated that all three southern Ips are able to detect all three compounds. This study examined the role of ipsdienol, ipsenol, and cis-verbenol in the chemical ecology of the southern Ips in Georgia and Louisiana. The most attractive blends of pheromones, with the fewest number of components, were ipsdienol plus ipsenol for I. avulsus, cis-verbenol plus ipsdienol for I. calligraphus, and either cis-verbenol plus ipsenol or ipsdienol plus ipsenol for I. grandicollis. Cross-attraction of I. grandicollis to the pheromone blend most attractive to I. avulsus was observed. Although the presence of heterospecific pheromone reduced the catches of all three species (i.e., the tertiary blend captured fewer beetles than the most attractive binary blends) in both states (significantly in two cases), high numbers of all three species were still captured in traps baited with all three compounds. These results suggest that the pheromones cis-verbenol, ipsdienol, and ipsenol can be combined for monitoring all three species of the southern Ips simultaneously. PMID:22812131

Allison, Jeremy D; McKenney, Jessica L; Miller, Daniel R; Gimmel, Matthew L

2012-06-01

337

Neuroprotective effects of volume-regulated anion channel blocker DCPIB on neonatal hypoxic-ischemic injury  

PubMed Central

Aim: To evaluate the role of swelling-induced activation of volume-regulated anion channels (VRACs) in a neonatal hypoxic-ischemic injury model using the selective VRAC blocker 4-(2-butyl-6,7-dichloro-2-cyclopentyl-indan-1-on5-yl) oxobutyric acid (DCPIB). Methods: Cerebral hypoxic-ischemic injury was induced in 7-day-old mouse pups with Rice-Vannucci method. Prior to the onset of ischemia, the animals were ip administered DCPIB (10 mg/kg). The animals were sacrificed 24 h afterwards, coronal sections of the brains were cut and the areas of infarct were examined using TTC staining and an image-analysis system. Cultured PC12 cells were subjected to oxygen-glucose deprivation (OGD) for 4 h. The cellular viability was assessed using Cell Counting Kit 8. Intracellular chloride concentration [Cl?]i was measured using 6-methoxy-N-ethylquinolinium iodide. Results: DCPIB-treated mice showed a significant reduction in hemispheric corrected infarct volume (26.65%±2.23%) compared to that in vehicle-treated mice (45.52%±1.45%, P<0.001). DCPIB-treated mice also showed better functional recovery as they were more active than vehicle-treated mice at 4 and 24 h post injury. In cultured PC12 cells, DCPIB (10 ?mol/L) significantly reduced OGD-induced cell death. Moreover, DCPIB (20 ?mol/L) blocked hypotonic-induced decrease in [Cl?]i in PC12 cells of both control and OGD groups. Conclusion: The results further support the pathophysiological role of VRACs in ischemic brain injury, and suggest DCPIB as a potential, easily administrable agent targeting VRACs in the context of perinatal and neonatal hypoxic-ischemic brain injury. PMID:23202801

Alibrahim, Ammar; Zhao, Li-yan; Bae, Christine You-jin; Barszczyk, Andrew; Lf Sun, Christopher; Wang, Guan-lei; Sun, Hong-shuo

2013-01-01

338

Citalopram Enhances Neurovascular Regeneration and Sensorimotor Functional Recovery after Ischemic Stroke in Mice  

PubMed Central

Recent clinical trials have demonstrated that treatment with selective serotonin reuptake inhibitors (SSRIs) after stroke enhances motor functional recovery; however, the underlying mechanisms remain to be further elucidated. We hypothesized that daily administration of the clinical drug citalopram would produce these functional benefits via enhancing neurovascular repair in the ischemic peri-infarct region. To test this hypothesis, focal ischemic stroke was induced in male C57/B6 mice by permanent ligation of distal branches of the middle cerebral artery to the barrel cortex and 7-min occlusion of the bilateral common carotid arteries. Citalopram (10 mg/kg, i.p.) was injected 24 hrs after stroke and daily thereafter. To label proliferating cells, bromo-deoxyuridine was injected daily beginning 3 days after stroke. Immunohistochemical and functional assays were performed to elucidate citalopram-mediated cellular and sensorimotor changes after stroke. Citalopram treatment had no significant effect on infarct formation or edema 3 days after stroke; however, citalopram-treated mice had better functional recovery than saline-treated controls 3 and 14 days after stroke in the adhesive removal test. Increased expression of brain derived neurotrophic factor was detected in the peri-infarct region 7 days after stroke in citalopram-treated animals. The number of proliferating neural progenitor cells and the distance of neuroblast migration from the sub-ventricular zone towards the ischemic cortex were significantly greater in citalopram-treated mice at 7 days after stroke. Immunohistochemical staining and co-localization analysis showed that citalopram-treated animals generated more new neurons and microvessels in the peri-infarct region 21 and 28 days after stroke. Taken together, these results suggest that citalopram promotes post-stroke sensorimotor recovery likely via enhancing neurogenesis, neural cell migration and the microvessel support in the peri-infarct region of the ischemic brain. PMID:23590907

Espinera, Alyssa R.; Ogle, Molly E.; Gu, Xiaohuan; Wei, Ling

2013-01-01

339

Antennal olfactory responsiveness of three sympatricIps species [Ips avulsus (Eichhoff),Ips calligraphus (Germar),Ips grandicollis (Eichhoff)], to intra- and interspecific behavioral chemicals.  

PubMed

Electroantennograms (EAGs) from male and femaleIps avulsus, I. calligraphus, andI. grandicollis to their pheromones and selected host odorants or kairomones verified the presence of antennal olfactory receptors in both sexes of each species capable of detecting ipsdienol, ipsenol,cis- andtrans-verbenol,endo-brevicomin ?-pinene, frontalin, and verbenone. Each species possesses receptors with lower thresholds and in greater abundance for the compounds they produce and to which they are behaviorally most responsive. Detection of bothIps andDendroctonus pheromones by the three cohabiting species provides a sensory basis for olfactory interactions among the species. Differences in both threshold and saturation levels for EAGs for the various behavioral chemicals could denote differences in specific behavioral roles for each compound. PMID:24276211

Smith, M T; Busch, G R; Payne, T L; Dickens, J C

1988-04-01

340

DETERMINATION OF AN EMPIRICALLY DERIVED IP/TSP RELATIONSHIP  

EPA Science Inventory

The primary objective of this study was to provide researchers with statistical methodology for comparing data on inhalable particulate (IP) and on the IP/TSP ratios from various sites, predicting IP concentration as a function of total suspended particulate (TSP) concentration, ...

341

Flow Labelled IP: A Connectionless Approach to ATM  

Microsoft Academic Search

A number of proposals for s upporting IP over ATM are under discussion in the networking community including: LAN emulation, classical IP over ATM, routing over large c louds, and multiprotocol over ATM. Each o f these proposals hides the real network topology from the IP layer by treating the data link layer as a large, opaque, network c loud.

Peter Newman; Thomas L. Lyon; Greg Minshall

1996-01-01

342

Traffic engineering standards in IP-networks using MPLS  

Microsoft Academic Search

The explosive growth of the Internet over the last few years has made the IP protocol suite the most predominant networking technology. Furthermore, the convergence of voice and data communications over a single network infrastructure is expected to happen over IP-based networks. Traditional IP-networks offer little predictability of service, which is often unacceptable for applications such as telephony, as well

A. Ghanwani; B. Jamoussi; D. Fedyk; P. Ashwood-Smith; Li Li; N. Feldman

1999-01-01

343

Characterizing Human Effort in Wireless Voice Over IP  

E-print Network

;Abstract Skype Voice Over IP (VoIP) traces from an experimental WiFi network were analyzed to detect simulations of a WiFi VoIP network to evaluate the effectiveness of dynamic resource allocation in addressing from a nearby WiFi access point operating in the same frequency, users naturally put some human

New South Wales, University of

344

Integration of Open Source and Enterprise IP PBXs  

Microsoft Academic Search

Over the last few years, voice over Internet protocol (VoIP) evolved from enabling voice communications between computer terminals to providing much wider functionality of the public switched telephony network (PSTN). The idea of deploying VoIP in private branch exchanges (PBXs) is gaining credence among service providers, and this paper addresses some of the design issues related to an IP PBX

Krishna Sumanth Chava; J. How

2007-01-01

345

Voices, I hear voices [VoIP security  

Microsoft Academic Search

The realm of computer networks already plagued with security and privacy concerns is a fertile ground for both offensive and defensive information security practitioners. In this paper, the author delves into the new security and privacy challenges the ongoing widespread adoption of IP telephony and voice over IP (VoIP) pose

Ivan Arce

2006-01-01

346

Convergent IPTV Services over IP Multimedia Alia Bellabas  

E-print Network

Convergent IPTV Services over IP Multimedia Subsystem Alia Bellabas IRISA, INSA Rennes alia.najah@orange-ftgroup.com Abstract--IP multimedia Subsystem (IMS) is one the most promising architectures for IP Television (IPTV audiovisual experience on both fixed and mobile devices over an IMS IPTV architecture as specified

Boyer, Edmond

347

ibm.com/redbooks TCP/IP Tutorial and  

E-print Network

ibm.com/redbooks TCP/IP Tutorial and Technical Overview Lydia Parziale David T. Britt Chuck Davis Jason Forrester Wei Liu Carolyn Matthews Nicolas Rosselot Understand networking fundamentals of the TCP/IP protocol suite Introduces advanced concepts and new technologies Includes the latest TCP/IP protocols Front

348

Full TCP/IP for 8-Bit Architectures Adam Dunkels  

E-print Network

Full TCP/IP for 8-Bit Architectures Adam Dunkels Swedish Institute of Computer Science adam@sics.se, http://www.sics.se/~adam/ Abstract We describe two small and portable TCP/IP implemen- tations fulfilling the subset of RFC1122 requirements needed for full host-to-host interoperability. Our TCP/IP

349

Cellular IP: a new approach to Internet host mobility  

Microsoft Academic Search

This paper describes a new approach to Internet host mobility. We argue that by separating local and wide area mobility, the performance of existing mobile host protocols (e.g. Mobile IP) can be significantly improved. We propose Cellular IP, a new lightweight and robust protocol that is optimized to support local mobility but efficiently interworks with Mobile IP to provide wide

András Gergely Valkó

1999-01-01

350

Effects of hypoxic preconditioning on synaptic ultrastructure in mice.  

PubMed

Hypoxic preconditioning (HPC) elicits resistance to more drastic subsequent insults, which potentially provide neuroprotective therapeutic strategy, but the underlying mechanisms remain to be fully elucidated. Here, we examined the effects of HPC on synaptic ultrastructure in olfactory bulb of mice. Mice underwent up to five cycles of repeated HPC treatments, and hypoxic tolerance was assessed with a standard gasp reflex assay. As expected, HPC induced an increase in tolerance time. To assess synaptic responses, Western blots were used to quantify protein levels of representative markers for glia, neuron, and synapse, and transmission electron microscopy was used to examine synaptic ultrastructure and mitochondrial density. HPC did not significantly alter the protein levels of astroglial marker (GFAP), neuron-specific markers (GAP43, Tuj-1, and OMP), synaptic number markers (synaptophysin and SNAP25) or the percentage of excitatory synapses versus inhibitory synapses. However, HPC significantly affected synaptic curvature and the percentage of synapses with presynaptic mitochondria, which showed concomitant change pattern. These findings demonstrate that HPC is associated with changes in synaptic ultrastructure. Synapse 69:7-14, 2015. © 2014 Wiley Periodicals, Inc. PMID:25155519

Liu, Yi; Sun, Zhishan; Sun, Shufeng; Duan, Yunxia; Shi, Jingfei; Qi, Zhifeng; Meng, Ran; Sun, Yongxin; Zeng, Xianwei; Chui, Dehua; Ji, Xunming

2015-01-01

351

Modulation of cardiac Na+,K+-ATPase cell surface abundance by simulated ischemia-reperfusion and ouabain preconditioning  

PubMed Central

Na+,K+-ATPase and cell survival were investigated in a cellular model of ischemia-reperfusion (I/R)-induced injury and protection by ouabain-induced preconditioning (OPC). Rat neonatal cardiac myocytes were subjected to 30 min of substrate and coverslip-induced ischemia followed by 30 min of simulated reperfusion. This significantly compromised cell viability as documented by lactate dehydrogenase release and Annexin V/propidium iodide staining. Total Na+,K+-ATPase ?1- and ?3-polypeptide expression remained unchanged, but cell surface biotinylation and immunostaining studies revealed that ?1-cell surface abundance was significantly decreased. Na+,K+-ATPase-activity in crude homogenates and 86Rb+ transport in live cells were both significantly decreased by about 30% after I/R. OPC, induced by a 4-min exposure to 10 ?M ouabain that ended 8 min before the beginning of ischemia, increased cell viability in a PKC?-dependent manner. This was comparable with the protective effect of OPC previously reported in intact heart preparations. OPC prevented I/R-induced decrease of Na+,K+-ATPase activity and surface expression. This model also revealed that Na+,K+-ATPase-mediated 86Rb+ uptake was not restored to control levels in the OPC group, suggesting that the increased viability was not conferred by an increased Na+,K+-ATPase-mediated ion transport capacity at the cell membrane. Consistent with this observation, transient expression of an internalization-resistant mutant form of Na+,K+-ATPase ?1 known to have increased surface abundance without increased ion transport activity successfully reduced I/R-induced cell death. These results suggest that maintenance of Na+,K+-ATPase cell surface abundance is critical to myocyte survival after an ischemic attack and plays a role in OPC-induced protection. They further suggest that the protection conferred by increased surface expression of Na+,K+-ATPase may be independent of ion transport. PMID:23086991

Belliard, Aude; Sottejeau, Yoann; Duan, Qiming; Karabin, Jessa L.

2013-01-01

352

Research study on IPS digital controller design  

NASA Technical Reports Server (NTRS)

The performance is investigated of the simplified continuous-data model of the Instrument Pointing System (IPS). Although the ultimate objective is to study the digital model of the system, knowledge on the performance of the continuous-data model is important in the sense that the characteristics of the digital system should approach those of the continuous-data system as the sampling period approaches zero.

Kuo, B. C.; Folkerts, C.

1976-01-01

353

Antennal olfactory responsiveness of three sympatric Ips species [ Ips avulsus (Eichhoff), Ips calligraphus (Germar), Ips grandicollis (Eichhoff)], to intra- and interspecific behavioral chemicals  

Microsoft Academic Search

Electroantennograms (EAGs) from male and femaleIps avulsus, I. calligraphus, andI. grandicollis to their pheromones and selected host odorants or kairomones verified the presence of antennal olfactory receptors in both sexes of each species capable of detecting ipsdienol, ipsenol,cis- andtrans-verbenol,endo-brevicomin a-pinene, frontalin, and verbenone. Each species possesses receptors with lower thresholds and in greater abundance for the compounds they produce and

M. T. Smith; G. R. Busch; T. L. Payne; J. C. Dickens

1988-01-01

354

The IP war: apocalypse or revolution?  

Microsoft Academic Search

In the Foundation series, Asimov predicted a 1,000 years of darkness following the fall of the galactic empire. In the book Noir, K.W Jeter describes a world where IP is the ultimate war. Combine them together and you have likely scenario No. 1.The Internet era enabled communication and information exchange on a global scale. But it also opened the door

Tsvi Gal; Howard M. Singer; Laird Popkin

2003-01-01

355

IP3 Receptor-Operated Calcium Entry  

NSDL National Science Digital Library

This Perspective by Mikoshiba and Hattori is the third in a series on cellular calcium release mechanisms. The authors describe the regulated release of calcium from intracellular stores by the inositol 1,4,5 trisphosphate receptor (IP3R) and the relationship of this release mechanism to calcium influx from the extracellular milieu through store-operated calcium channels. They discuss a model proposing that intracellular and plasma membrane calcium channels are functionally and physically coupled.

Katsuhiko Mikoshiba (Japan;University of Tokyo and the Laboratory for Developmental Neurobiology REV); Mitsuharu Hattori (Japan;University of Tokyo and the Laboratory for Developmental Neurobiology REV)

2000-09-26

356

Importance of timing of magnesium administration in the isolated ischemic-reperfused rat heart: role of K(ATP) channels.  

PubMed

There is a growing interest for the beneficial effect of magnesium (Mg) in cardiovascular disorders. A number of cardiovascular disorders including myocardial infarction, arrhythmias and congestive heart failure have been associated with low extra- cellular or intracellular concentrations of Mg. The efficiency of the preconditioning effect of Mg on cardiac function and infarct size in the globally ischemic-reperfused isolated rat heart was studied together with the role of ATP-sensitive potassium (K(ATP)) channels in protection induced by Mg. Rat hearts were Langendorff perfused, subjected to 30 min of global ischemia and 90 min of reperfusion, including treatment groups which focused on different times of Mg (8 mmol/l) use. Infarct size was measured by triphenyltetrazolium chloride (TTC) method. The left ventricular function was assessed by left ventricular developed pressure (LVDP), heart rate (HR) and coronary flow (CF). The administration of Mg before ischemia had an anti-infarct effect in rat hearts and improved cardiac function. The protective effects of magnesium was abolished by the blocking of K(ATP) channels and suggests that K-ATP channel has an important role in the heart protection effect of Mg as a preconditioning agent. PMID:18052684

Bazargan, M; Faghihi, M; Chitsaz, M

2008-01-01

357

Ocular ischemic syndrome - a systematic review  

PubMed Central

Summary Ocular ischemic syndrome is a rare condition, which is caused by ocular hypoperfusion due to stenosis or occlusion of the common or internal carotid arteries. Atherosclerosis is the major cause of changes in the carotid arteries. Ocular ischemic syndrome is manifested as visual loss, orbital pain and, frequently, changes of the visual field, and various anterior and posterior segment signs. Anterior segment signs include iris neovascularization and secondary neovascular glaucoma, iridocyclitis, asymmetric cataract, iris atrophy and sluggish reaction to light. Posterior eye segment changes are the most characteristic, such as narrowed retinal arteries, perifoveal telangiectasias, dilated retinal veins, mid-peripheral retinal hemorrhages, microaneurysms, neovascularization at the optic disk and in the retina, a cherry-red spot, cotton-wool spots, vitreous hemorrhage and normal-tension glaucoma. Differential diagnosis of ocular ischemic syndrome includes diabetic retinopathy and moderate central retinal vein occlusion. Carotid artery imaging and fundus fluorescein angiography help to establish the diagnosis of ocular ischemic syndrome. The treatment can be local, for example, ocular (conservative, laser and surgical) or systemic (conservative and surgical treatment of the carotid artery). Since the condition does not affect the eyes alone, patients with ocular ischemic syndrome should be referred for consultation to the neurologist, vascular surgeon and cardiologist. PMID:22847215

Terelak-Borys, Barbara; Skonieczna, Katarzyna; Grabska-Liberek, Iwona

2012-01-01

358

I want my voice to be heard: IP over Voice-over-IP for unobservable censorship circumvention  

E-print Network

unobservability against traffic analysis and standard censorship techniques. Keywords-Internet Censorship the Internet. Censorship devices leverage various techniques [2], [3] ranging from simple IP address blockingI want my voice to be heard: IP over Voice-over-IP for unobservable censorship circumvention Amir

Borisov, Nikita

359

Ischemic stroke in prediabetic patients.  

PubMed

To describe the clinical characteristics of first-ever ischemic stroke (IS) patients with prediabetes, and to compare them with diabetes mellitus (DM) and non-DM patient characteristics. Retrospective analysis of a prospective series of first-ever acute IS patients. Patients were classified as non-DM (HbA1c during admission <5.7 % and no previous evidence of 2 or more fasting glucose >126 mg/dL), prediabetes (HbA1c from 5.7 to 6.4 %), and DM (previous DM diagnosis or HbA1c ?6.5 % independently of current blood glucose). Demographic and clinical characteristics were compared between the three groups, along with outcome data [early neurological deterioration (END), 3-month poor outcome, 3-month mortality, outcome after rtPA treatment]. No demographic differences were observed. Prediabetic patients had more arterial hypertension (p = 0.006) and higher waist circumference (p < 0.0001) than non-DM patients, and DM patients had more hypercholesterolemia (p < 0.0001), body mass index (p = 0.017), and coronary artery disease (p = 0.005) than prediabetics. There were differences in TOAST subtype distribution (p < 0.0001). There were no differences in rtPA treatment success rate between groups. Multivariate analysis adjusted by age and stroke severity showed that DM but not prediabetes is an independent factor associated with END and 3-month poor outcome. Prediabetic patients with IS exhibit an "intermediate" vascular risk factor profile between that of non-DM and DM patients. In contrast to DM patients, IS prognosis in patients with prediabetes is similar to non-DM patients. PMID:25022941

Roquer, Jaume; Rodríguez-Campello, Ana; Cuadrado-Godia, Elisa; Giralt-Steinhauer, Eva; Jiménez-Conde, Jordi; Dégano, Irene R; Ois, Angel

2014-10-01

360

Inhibition of Myocardial Apoptosis by Ischaemic and Beta-Adrenergic Preconditioning is Dependent on p38 MAPK  

Microsoft Academic Search

Summary  Introduction: Apoptosis occurring during ischaemia \\/reperfusion contributes independently to tissue damage, and involves activation of\\u000a the stress-kinase, p38 MAPK during reperfusion. Ischaemic preconditioning (IPC) protects against ischaemia\\/reperfusion mediated\\u000a necrosis and apoptosis. The role of p38 MAPK in the protective effect of preconditioning against apoptosis is unknown. Pharmacologic\\u000a preconditioning with isoproterenol (?-PC) also protects against necrosis, but it is not known

Johannes A. Moolman; Shahiem Hartley; Johanna Van Wyk; Erna Marais; Amanda Lochner

2006-01-01

361

Impact of artifact removal on ChIP quality metrics in ChIP-seq and ChIP-exo data  

PubMed Central

With the advent of ChIP-seq multiplexing technologies and the subsequent increase in ChIP-seq throughput, the development of working standards for the quality assessment of ChIP-seq studies has received significant attention. The ENCODE consortium's large scale analysis of transcription factor binding and epigenetic marks as well as concordant work on ChIP-seq by other laboratories has established a new generation of ChIP-seq quality control measures. The use of these metrics alongside common processing steps has however not been evaluated. In this study, we investigate the effects of blacklisting and removal of duplicated reads on established metrics of ChIP-seq quality and show that the interpretation of these metrics is highly dependent on the ChIP-seq preprocessing steps applied. Further to this we perform the first investigation of the use of these metrics for ChIP-exo data and make recommendations for the adaptation of the NSC statistic to allow for the assessment of ChIP-exo efficiency. PMID:24782889

Carroll, Thomas S.; Liang, Ziwei; Salama, Rafik; Stark, Rory; de Santiago, Ines

2014-01-01

362

Glycine transporters type 1 inhibitor promotes brain preconditioning against NMDA-induced excitotoxicity.  

PubMed

Brain preconditioning is a protective mechanism, which can be activated by sub-lethal stimulation of the NMDA receptors (NMDAR) and be used to achieve neuroprotection against stroke and neurodegenerative diseases models. Inhibitors of glycine transporters type 1 modulate glutamatergic neurotransmission through NMDAR, suggesting an alternative therapeutic strategy of brain preconditioning. The aim of this work was to evaluate the effects of brain preconditioning induced by NFPS, a GlyT1 inhibitor, against NMDA-induced excitotoxicity in mice hippocampus, as well as to study its neurochemical mechanisms. C57BL/6 mice (male, 10-weeks-old) were preconditioned by intraperitoneal injection of NFPS at doses of 1.25, 2.5 or 5.0 mg/kg, 24 h before intrahippocampal injection of NMDA. Neuronal death was evaluated by fluoro jade C staining and neurochemical parameters were evaluated by gas chromatography-mass spectrometry, scintillation spectrometry and western blot. We observed that NFPS preconditioning reduced neuronal death in CA1 region of hippocampus submitted to NMDA-induced excitotoxicity. The amino acids (glycine and glutamate) uptake and content were increased in hippocampus of animals treated with NFPS 5.0 mg/kg, which were associated to an increased expression of type-2 glycine transporter (GlyT2) and glutamate transporters (EAAT1, EAAT2 and EAAT3). The expression of GlyT1 was reduced in animals treated with NFPS. Interestingly, the preconditioning reduced expression of GluN2B subunits of NMDAR, whereas did not change the expression of GluN1 or GluN2A in all tested doses. Our study suggests that NFPS preconditioning induces resistance against excitotoxicity, which is associated with neurochemical changes and reduction of GluN2B-containing NMDAR expression. PMID:25312280

Cunha Xavier Pinto, Mauro; Lima, Isabel Vieira de Assis; Pessoa da Costa, Flávia Lage; Rosa, Daniela Valadão; Mendes-Goulart, Vânia Aparecida; Resende, Rodrigo Ribeiro; Romano-Silva, Marco Aurélio; Pinheiro de Oliveira, Antônio Carlos; Gomez, Marcus Vinícius; Gomez, Renato Santiago

2015-02-01

363

Lipopolysaccharide preconditioning facilitates M2 activation of resident microglia after spinal cord injury.  

PubMed

The inflammatory response following spinal cord injury (SCI) has both harmful and beneficial effects; however, it can be modulated for therapeutic benefit. Endotoxin/lipopolysaccharide (LPS) preconditioning, a well-established method for modifying the immune reaction, has been shown to attenuate damage induced by stroke and brain trauma in rodent models. Although such effects likely are conveyed by tissue-repairing functions of the inflammatory response, the mechanisms that control the effects have not yet been elucidated. The present study preconditioned C57BL6/J mice with 0.05 mg/kg of LPS 48 hr before inducing contusion SCI to investigate the effect of LPS preconditioning on the activation of macrophages/microglia. We found that LPS preconditioning promotes the polarization of M1/M2 macrophages/microglia toward an M2 phenotype in the injured spinal cord on quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and immunohistochemical analyses. Flow cytometric analyses reveal that LPS preconditioning facilitates M2 activation in resident microglia but not in infiltrating macrophages. Augmented M2 activation was accompanied by vascularization around the injured lesion, resulting in improvement in both tissue reorganization and functional recovery. Furthermore, we found that M2 activation induced by LPS preconditioning is regulated by interleukin-10 gene expression, which was preceded by the transcriptional activation of interferon regulatory factor (IRF)-3, as demonstrated by Western blotting and an IRF-3 binding assay. Altogether, our findings demonstrate that LPS preconditioning has a therapeutic effect on SCI through the modulation of M1/M2 polarization of resident microglia. The present study suggests that controlling M1/M2 polarization through endotoxin signal transduction could become a promising therapeutic strategy for various central nervous system diseases. © 2014 Wiley Periodicals, Inc. PMID:25044014

Hayakawa, Kentaro; Okazaki, Rentaro; Morioka, Kazuhito; Nakamura, Kozo; Tanaka, Sakae; Ogata, Toru

2014-12-01

364

IP address management : augmenting Sandia's capabilities through open source tools.  

SciTech Connect

Internet Protocol (IP) address management is an increasingly growing concern at Sandia National Laboratories (SNL) and the networking community as a whole. The current state of the available IP addresses indicates that they are nearly exhausted. Currently SNL doesn't have the justification to obtain more IP address space from Internet Assigned Numbers Authority (IANA). There must exist a local entity to manage and allocate IP assignments efficiently. Ongoing efforts at Sandia have been in the form of a multifunctional database application notably known as Network Information System (NWIS). NWIS is a database responsible for a multitude of network administrative services including IP address management. This study will explore the feasibility of augmenting NWIS's IP management capabilities utilizing open source tools. Modifications of existing capabilities to better allocate available IP address space are studied.

Nayar, R. Daniel

2005-08-01

365

Source identification of the Arctic sea ice proxy IP25.  

PubMed

Analysis of the organic geochemical biomarker IP25 in marine sediments is an established method for carrying out palaeo sea ice reconstructions for the Arctic. Such reconstructions cover timescales from decades back to the early Pleistocene, and are critical for understanding past climate conditions on Earth and for informing climate prediction models. Key attributes of IP25 include its strict association with Arctic sea ice together with its ubiquity and stability in underlying marine sediments; however, the sources of IP25 have remained undetermined. Here we report the identification of IP25 in three (or four) relatively minor (<5%) sea ice diatoms isolated from mixed assemblages collected from the Canadian Arctic. In contrast, IP25 was absent in the dominant taxa. Chemical and taxonomical investigations suggest that the IP25-containing taxa represent the majority of producers and are distributed pan-Arctic, thus establishing the widespread applicability of the IP25 proxy for palaeo Arctic sea ice reconstruction. PMID:24939562

Brown, T A; Belt, S T; Tatarek, A; Mundy, C J

2014-01-01

366

Source identification of the Arctic sea ice proxy IP25  

NASA Astrophysics Data System (ADS)

Analysis of the organic geochemical biomarker IP25 in marine sediments is an established method for carrying out palaeo sea ice reconstructions for the Arctic. Such reconstructions cover timescales from decades back to the early Pleistocene, and are critical for understanding past climate conditions on Earth and for informing climate prediction models. Key attributes of IP25 include its strict association with Arctic sea ice together with its ubiquity and stability in underlying marine sediments; however, the sources of IP25 have remained undetermined. Here we report the identification of IP25 in three (or four) relatively minor (<5%) sea ice diatoms isolated from mixed assemblages collected from the Canadian Arctic. In contrast, IP25 was absent in the dominant taxa. Chemical and taxonomical investigations suggest that the IP25-containing taxa represent the majority of producers and are distributed pan-Arctic, thus establishing the widespread applicability of the IP25 proxy for palaeo Arctic sea ice reconstruction.

Brown, T. A.; Belt, S. T.; Tatarek, A.; Mundy, C. J.

2014-06-01

367

Spectroscopic Monitoring of Kidney Tissue Ischemic Injury  

SciTech Connect

Noninvasive evaluation of tissue viability of donor kidneys used for transplantation is an issue that current technology is not able to address. In this work, we explore optical spectroscopy for its potential to assess the degree of ischemic damage in kidney tissue. We hypothesized that ischemic damage to kidney tissue will give rise to changes in its optical properties which in turn may be used to asses the degree of tissue injury. The experimental results demonstrate that the autofluorescence intensity of the injured kidney is decreasing as a function of time exposed to ischemic injury. Changes were also observed in the NIR light scattering intensities most probably arising from changes due to injury and death of the tissue.

Demos, S G; Fitzgerald, J T; Michalopoulou, A P; Troppmann, C

2004-03-11

368

Ischemic stroke subtypes: risk factors, functional outcome and recurrence  

Microsoft Academic Search

.   The etiology of ischemic stroke affects its prognosis, outcome and management. Our aims were to determine risk factors, clinical\\u000a and imaging variables and prognostic differences in acute ischemic stroke subtypes. In this study, we prospectively investigated\\u000a 264 consecutive patients with acute ischemic stroke between 1996 and 2000. All of the patients were categorized to one of\\u000a four major ischemic

M. Murat Sumer; O. Erturk

2002-01-01

369

Human Amniotic Fluid Stem Cell Preconditioning Improves Their Regenerative Potential  

PubMed Central

Human amniotic fluid stem (hAFS) cells, a novel class of broadly multipotent stem cells that share characteristics of both embryonic and adult stem cells, have been regarded as promising candidate for cell therapy. Taking advantage by the well-established murine model of acute kidney injury (AKI), we studied the proregenerative effect of hAFS cells in immunodeficient mice injected with the nephrotoxic drug cisplatin. Infusion of hAFS cells in cisplatin mice improved renal function and limited tubular damage, although not to control level, and prolonged animal survival. Human AFS cells engrafted injured kidney predominantly in peritubular region without acquiring tubular epithelial markers. Human AFS cells exerted antiapoptotic effect, activated Akt, and stimulated proliferation of tubular cells possibly via local release of factors, including interleukin-6, vascular endothelial growth factor, and stromal cell–derived factor-1, which we documented in vitro to be produced by hAFS cells. The therapeutic potential of hAFS cells was enhanced by cell pretreatment with glial cell line–derived neurotrophic factor (GDNF), which markedly ameliorated renal function and tubular injury by increasing stem cell homing to the tubulointerstitial compartment. By in vitro studies, GDNF increased hAFS cell production of growth factors, motility, and expression of receptors involved in cell homing and survival. These findings indicate that hAFS cells can promote functional recovery and contribute to renal regeneration in AKI mice via local production of mitogenic and prosurvival factors. The effects of hAFS cells can be remarkably enhanced by GDNF preconditioning. PMID:22066606

Rota, Cinzia; Imberti, Barbara; Pozzobon, Michela; Piccoli, Martina; De Coppi, Paolo; Atala, Anthony; Gagliardini, Elena; Xinaris, Christodoulos; Benedetti, Valentina; Fabricio, Aline S.C.; Squarcina, Elisa; Abbate, Mauro; Benigni, Ariela; Remuzzi, Giuseppe

2012-01-01

370

Houston's unusually large hourly ozone increases: Preconditions and geographical origins  

NASA Astrophysics Data System (ADS)

Many of Houston's highest measured 8-hr ozone (O3) peaks are characterized by sudden increases in concentrations of at least 40 ppb in one hour, or 60 ppb in two hours. Measurements show that these large hourly changes appear at only a few monitors and span a narrow geographic area suggesting a spatially heterogeneous field of O3 concentrations. Regulatory air quality modeling has been unable to reproduce the magnitude or location of some of the highest observed hourly O3 changes, and it also failed to capture the limited spatial extent. The cause(s) of these O3 events is an open question. Some observed large hourly changes in O3 concentrations have been linked to random releases of industrial volatile organic compounds (VOCs), and meteorological conditions are known to impact O3 formation in Houston. Days with rotating winds and low wind speeds often produce the greatest O3 concentrations, and the location of regional high-pressure zones also impact pollutant levels. It is unlikely, however, that meteorology alone can explain the rapid O3 increases. This work considers local and regional meteorological conditions and ambient VOC measurements in an attempt to determine the necessary preconditions for the large hourly O3 increases found in the observational record. Using over ten years of measurement data, we have identified candidate days with unusually large hourly O3 increases. We will combine wind field measurements, automated gas chromatograph data, and back trajectory modeling to determine the necessary conditions and likely geographical origins of the O3 events. Preliminary results show evidence for rapid photochemical production of O3 consistent with highly reactive plumes of oxidant precursors.

Couzo, E. A.; Jeffries, H. E.; Vizuete, W.

2012-12-01

371

Inflammatory responses in hypoxic ischemic encephalopathy  

PubMed Central

Inflammation plays a critical role in mediating brain injury induced by neonatal hypoxic ischemic encephalopathy (HIE). The mechanisms underlying inflammatory responses to ischemia may be shared by neonatal and adult brains; however, HIE exhibits a unique inflammation phenotype that results from the immaturity of the neonatal immune system. This review will discuss the current knowledge concerning systemic and local inflammatory responses in the acute and subacute stages of HIE. The key components of inflammation, including immune cells, adhesion molecules, cytokines, chemokines and oxidative stress, will be reviewed, and the differences between neonatal and adult inflammatory responses to cerebral ischemic injury will also be discussed. PMID:23892271

Liu, Fudong; Mccullough, Louise D

2013-01-01

372

The Siblings With Ischemic Stroke Study (SWISS) Protocol  

Microsoft Academic Search

BACKGROUND: Family history and twins studies suggest an inherited component to ischemic stroke risk. Candidate gene association studies have been performed but have limited capacity to identify novel risk factor genes. The Siblings With Ischemic Stroke Study (SWISS) aims to conduct a genome-wide scan in sibling pairs concordant or discordant for ischemic stroke to identify novel genetic risk factors through

James F Meschia; Robert D Brown Jr; Thomas G Brott; Felix E Chukwudelunzu; John Hardy; Stephen S Rich

2002-01-01

373

Autologous bone marrow cells and ischemic cardiomyopathy Jerome Roncalli1  

E-print Network

1 Autologous bone marrow cells and ischemic cardiomyopathy Jerome Roncalli1 , MD, PhD, Patricia: Intramyocardial stem cell injection in patients with ischemic cardiomyopathy: functional recovery and reverse of ischemic cardiomyopathy. A variety of adult stem and progenitor cells from different sources have already

Paris-Sud XI, Université de

374

Incidental Unruptured Intracranial Aneurysms in Patients with Acute Ischemic Stroke  

Microsoft Academic Search

Background: The management and clinical prognosis of incidental intracranial aneurysms in acute ischemic stroke patients have been understudied. We investigated the clinical outcome of acute ischemic stroke subjects with incidentally found intracranial aneurysms. Methods: We consecutively included acute ischemic stroke patients within 7 days of onset. Their demographics, risk factors, stroke subtypes, antithrombotics use and modified Rankin scale (mRS) at

Yoon-Sang Oh; Seung-Jae Lee; Young-Min Shon; Dong Won Yang; Beum Saeng Kim; A-Hyun Cho

2008-01-01

375

Spinal epidural hematoma after intravenous thrombolysis for acute ischemic stroke  

Microsoft Academic Search

Intracranial bleeding is an important and dangerous complication associated with thrombolytic therapy for acute ischemic stroke. Spinal hemorrhage has been reported after systemic thrombolysis for various conditions other than acute ischemic stroke. Our patient presented with an acute ischemic stroke and showed significant clinical recovery during intravenous thrombolysis. CT scan of the brain, performed about 6 h later due to neurological

Leonard L. L. Yeo; Joline Si Jing Lim; Vijay K. Sharma

2009-01-01

376

Ischemia preconditioning protects rat submandibular glands from ischemia/reperfusion injuries.  

PubMed

To investigate the effects of ischemia/reperfusion on rat submandibular glands without denervation and the possible protective effects of ischemia preconditioning on the glands that experienced ischemia/reperfusion, in-situ ischemia/reperfusion and ischemia preconditioning experimental models of submandibular glands of healthy male Wistar rats were conducted. For ischemia/reperfusion groups, the glands were subjected to 90 min of ischemia without denervation, followed by 1, 12, 24, or 72 h of reperfusion. Ischemia preconditioning was achieved by 3 min of ischemia following 3 min of reperfusion, performed three times before ischemia/reperfusion. Salivary secretion, histological changes, alterations of tight junctions, myeloperoxidase activity, cellular apoptosis, and reactive oxygen species levels were detected. In ischemia/reperfusion glands, rising acute-inflammation responses, reduced tight-junction width, and increased myeloperoxidase activity, reactive oxygen species levels, and apoptotic cell numbers were observed, along with secretory dysfunction, especially at 1 and 12 h post-reperfusion, which seemed to gradually return to normal by 72 h post-reperfusion. In contrast, ischemia preconditioning showed the potential to ameliorate the injury-stress responses caused by ischemia/reperfusion. Our study revealed that ischemia/reperfusion could cause a series of injury-stress responses and ultimately lead to hyposecretion, independently of the parasympathetic nerve supply, which might play an important role in the early-phase dysfunction of the transplanted glands. Ischemia preconditioning could protect the involved glands and improve ischemia/reperfusion-induced hyposecretion. PMID:25216112

Shi, Liang; Xiao, Meng; Dai, Mei-Lu; Liu, Shao-Hua; Liu, Yun-Sheng; Wei, Feng-Cai

2014-10-01

377

Gauss-Newton inspired preconditioned optimization in large deformation diffeomorphic metric mapping.  

PubMed

In this work, we propose a novel preconditioned optimization method in the paradigm of Large Deformation Diffeomorphic Metric Mapping (LDDMM). The preconditioned update scheme is formulated for the non-stationary and the stationary parameterizations of diffeomorphisms, yielding three different LDDMM methods. The preconditioning matrices are inspired in the Hessian approximation used in Gauss-Newton method. The derivatives are computed using Frechet differentials. Thus, optimization is performed in a Sobolev space, in contrast to optimization in L(2) commonly used in non-rigid registration literature. The proposed LDDMM methods have been evaluated and compared with their respective implementations of gradient descent optimization. Evaluation has been performed using real and simulated images from the Non-rigid Image Registration Evaluation Project (NIREP). The experiments conducted in this work reported that our preconditioned LDDMM methods achieved a performance similar or superior to well-established-in-literature gradient descent non-stationary LDDMM in the great majority of cases. Moreover, preconditioned optimization showed a substantial reduction in the execution time with an affordable increase of the memory usage per iteration. Additional experiments reported that optimization using Frechet differentials should be preferable to optimization using L(2) differentials. PMID:25254606

Hernandez, Monica

2014-10-21

378

Gauss–Newton inspired preconditioned optimization in large deformation diffeomorphic metric mapping  

NASA Astrophysics Data System (ADS)

In this work, we propose a novel preconditioned optimization method in the paradigm of Large Deformation Diffeomorphic Metric Mapping (LDDMM). The preconditioned update scheme is formulated for the non-stationary and the stationary parameterizations of diffeomorphisms, yielding three different LDDMM methods. The preconditioning matrices are inspired in the Hessian approximation used in Gauss–Newton method. The derivatives are computed using Frechet differentials. Thus, optimization is performed in a Sobolev space, in contrast to optimization in L2 commonly used in non-rigid registration literature. The proposed LDDMM methods have been evaluated and compared with their respective implementations of gradient descent optimization. Evaluation has been performed using real and simulated images from the Non-rigid Image Registration Evaluation Project (NIREP). The experiments conducted in this work reported that our preconditioned LDDMM methods achieved a performance similar or superior to well-established-in-literature gradient descent non-stationary LDDMM in the great majority of cases. Moreover, preconditioned optimization showed a substantial reduction in the execution time with an affordable increase of the memory usage per iteration. Additional experiments reported that optimization using Frechet differentials should be preferable to optimization using L2 differentials.

Hernandez, Monica

2014-10-01

379

In vitro synthesis and purification of PhIP-deoxyguanosine and PhIP-DNA oligomer covalent complexes  

SciTech Connect

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a heterocyclic amine compound formed when meats are cooked at high temperatures. PhIP damages DNA by forming covalent complexes with DNA carcinogen. In an effort to understand how the binding of PhIP to DNA may cause cancer, it is important to characterize the structures of PhIP-damaged DNA molecules. Our HPLC data support fluorescence and {sup 32}P Post-labeling studies which indicate the formation of several species of 2{prime}deoxyguanosine-(dG) or oligodeoxynucleotide-PhIP adducts. The reaction of PhIP with dG resulted in a reddish precipitate that was likely the major adduct, N-(deoxyguanosin-8-yl)-PhIP (dG-C8-PhIP) adduct, with a more polar adduct fraction remaining in the supernatant. Reversed-phase HPLC analysis of the adducts in the supernatant revealed the existence of species of much shorter retention times than the dG-C8-PhIP adduct, confirming that these species are more polar than dG-C8-PhIP. At least four adducts were formed in the reaction of PhIP with DNA oligomer. HPLC analysis of the PhIP-DNA oligomer supernatant after butanol extractions revealed four unresolved peaks which spectra had maximum wavelengths between 340 and 360 nm. Though adduct peaks were not completely resolved, there was {approximately}3 minutes interval between the DNA oligomer peak and the adduct peaks. Furthermore, fluorescence emission data of the DNA oligomer-PhIP adduct solution show heterogeneous binding. The more polar PhIP adducts were fraction-collected and their structures will be solved by nuclear magnetic resonance or x-ray crystallography.

Freeman, J.

1994-12-01

380

Long-Term Outcomes of Ischemic Stroke Patients with Concurrent Intracranial and Extracranial Stenoses and Ischemic Heart Disease  

Microsoft Academic Search

Background and Purpose: Coexisting ischemic heart disease (IHD) and concurrent atherosclerosis of intracranial and extracranial vessels is common in Asians. This study aims to investigate the long-term outcomes of ischemic stroke patients with concurrent stenoses and IHD. Methods: This was a prospective cohort study in Hong Kong. Consecutive Chinese patients with acute ischemic stroke underwent MRI, magnetic resonance angiography and

B. L. Man; Y. P. Fu; Y. Y. Chan; W. Lam; C. F. Hui; W. H. Leung; V. Mok; K. S. Wong

2010-01-01

381

Normalization of ChIP-seq data with control  

PubMed Central

Background ChIP-seq has become an important tool for identifying genome-wide protein-DNA interactions, including transcription factor binding and histone modifications. In ChIP-seq experiments, ChIP samples are usually coupled with their matching control samples. Proper normalization between the ChIP and control samples is an essential aspect of ChIP-seq data analysis. Results We have developed a novel method for estimating the normalization factor between the ChIP and the control samples. Our method, named as NCIS (Normalization of ChIP-seq) can accommodate both low and high sequencing depth datasets. We compare statistical properties of NCIS against existing methods in a set of diverse simulation settings, where NCIS enjoys the best estimation precision. In addition, we illustrate the impact of the normalization factor in FDR control and show that NCIS leads to more power among methods that control FDR at nominal levels. Conclusion Our results indicate that the proper normalization between the ChIP and control samples is an important step in ChIP-seq analysis in terms of power and error rate control. Our proposed method shows excellent statistical properties and is useful in the full range of ChIP-seq applications, especially with deeply sequenced data. PMID:22883957

2012-01-01

382

2011 Raj JainCSE571SWashington University in St. Louis IP SecurityIP Security  

E-print Network

SWashington University in St. Louis OverviewOverview 1. IPSec 2. Authentication Header (AH) 3. EncapsulatingIP Security IPSec provides Access control: User authentication Data integrity Data origin authentication, Extranets Ref: http://en.wikipedia.org/wiki/IPsec #12;19-4 ©2011 Raj JainCSE571SWashington University in St

Jain, Raj

383

Live Video and IP-TV  

NASA Astrophysics Data System (ADS)

This Chapter aims at providing a comprehensive insight into the most recent advances in the field of P2P architectures for video broadcasting, focusing on live video streaming P2P live video streaming . After introducing a classification of P2P video solutions, the first part of the Chapter provides an overview of the most interesting P2P IP-TV P2P IP-TV systems currently available over the Internet. It also concentrates on the process of data diffusion within the P2P overlay and complements this view with some measurements that highlight the most salient features of P2P architectures. The second part of the Chapter completes the view, bringing up the modeling efforts to capture the main characteristics and limits of P2P streaming systems, both analytically and numerically. The Chapter is closed by a pristine look at some challenging, open questions, with a specific emphasis on the adoption of network coding in P2P streaming solutions.

Merani, Maria Luisa; Saladino, Daniela

384

Metabolic Prosthesis for Oxygenation of Ischemic Tissue  

Microsoft Academic Search

This communication discloses new ideas and preliminary results on the development of a metabolic prosthesis for local oxygenation of ischemic tissue under physiologically neutral conditions. We report for the first time selective electrolysis of physiological saline by repetitively pulsed, charge-limited electrolysis for the production of oxygen and suppression of free chlorine. Using 800-mu A amplitude current pulses and < 200

Elias Greenbaum; Mark S. Humayun; Charlene A. Sanders; D. Close; H. M. O'Neill; B. R. Evans

2009-01-01

385

Ischemic stroke: carotid and vertebral artery disease  

Microsoft Academic Search

Ischemic strokes may have distinct aetiologies, including several different intrinsic arterial pathological disorders. The diagnosis and understanding of these arterial diseases is critical for the correct management of stroke as different treatment approaches are undertaken according to the aetiology. Atherosclerosis is by far the most common arterial disease among adults, and other pathological processes include arterial dissection, small vessel disease,

P. Vilela; A. Goulão

2005-01-01

386

Cell Based Therapies for Ischemic Tissue Repair  

Cancer.gov

As the population ages and the acute mortality from cardiovascular disease decreases, a large population of patients is emerging who have symptomatic chronic ischemic cardiac and vascular disease, many of whom remain severely symptomatic despite exhausting conventional medical therapy and mechanical revascularization. Mounting evidence suggests that microvascular insufficiency plays a significant role in the pathophysiology of ischemia.

387

Gene therapy for ischemic heart disease  

Microsoft Academic Search

Current pharmacologic therapy for ischemic heart disease suffers multiple limitations such as compliance issues and side effects of medications. Revascularization procedures often end with need for repeat procedures. Patients remain symptomatic despite maximal medical therapy. Gene therapy offers an attractive alternative to current pharmacologic therapies and may be beneficial in refractory disease. Gene therapy with isoforms of growth factors such

Madhav Lavu; Susheel Gundewar; David J. Lefer

2011-01-01

388

Apoptosis, Heart Failure, Ischemic Heart Disease  

Microsoft Academic Search

Cardiomyocytes die by apoptosis in addition to necrosis under a variety of pathological conditions including heart failure, cardiomyopathy, and ischemia\\/reperfusion. This review summarizes current status of the literature demonstrating evidence of apoptotic cell death in heart failure and ischemic heart disease. Apoptotic cells have been detected in failing hearts of human and dog. Ischemia up to 2 hr does not

Nilanjana Maulik; Dipak K. Das

1999-01-01

389

Primary Prevention in Chronic Ischemic Heart Disease  

Microsoft Academic Search

Despite the remarkable advances in cardiovascular therapeutics over the last two decades, sudden death still remains a substantially large proportion of all deaths in patients with ischemic heart disease. Patients in the early stages of AMI are at high risk of dying suddenly, often from ventricular ~brillation [1]. Survivors of AMI, especially those with frequent ventricular ectopy, are also at

Koon K. Teo

1999-01-01

390

Stroke registry: hemorrhagic vs ischemic strokes  

Microsoft Academic Search

BackgroundEpidemiologic studies of stroke in the 1970s and 1980s have reported the percentage of ischemic stroke as 73% to 86%, with hemorrhagic stroke as only 8% to 18%; the remainder was undetermined (due to not performing computed tomographic [CT] scanning or an autopsy). In our clinical work, it appeared anecdotally to the authors that we were seeing more hemorrhagic strokes

Joseph R. Shiber; Emily Fontane; Ademola Adewale

2010-01-01

391

Vasoconstrictive neurovascular coupling during focal ischemic depolarizations  

E-print Network

Vasoconstrictive neurovascular coupling during focal ischemic depolarizations Hwa Kyoung Shin1 , Andrew K Dunn2 , Phillip B Jones2 , David A Boas2 , Michael A Moskowitz1 and Cenk Ayata1,3 1 Stroke, Massachusetts, USA; 2 Department of Radiology, Martinos Center for Biomedical Imaging, Massachusetts General

Boas, David

392

Hyperglycemia increases susceptibility to ischemic necrosis.  

PubMed

Diabetic patients are at risk for spontaneous foot ulcers, chronic wounds, infections, and tissue necrosis. Current theories suggest that the development and progression of diabetic foot ulcers are mainly caused by arteriosclerosis and peripheral neuropathy. Tissue necrosis plays a primordial role in the progression of diabetic foot ulcers but the underlying mechanisms are poorly understood. The aim of the present study was to investigate the effects of hyperglycemia per se on the susceptibility of ischemic tissue to necrosis, using a critical ischemic hind limb animal model. We inflicted the same degree of ischemia in both euglycemic and streptozotocin-induced hyperglycemic rats by resecting the external iliac, the femoral, and the saphenous arteries. Postoperative laser Doppler flowmetry of the ischemic feet showed the same degree of reduction in skin perfusion in both hyperglycemic and euglycemic animals. Nevertheless, we found a significantly higher rate of limb necrosis in hyperglycemic rats compared to euglycemic rats (71% versus 29%, resp.). In this study, we revealed that hyperglycemia per se increases the susceptibility to limb necrosis in ischemic conditions. Our results may help to better understand the physiopathology of progressive diabetic wounds and underline the importance of strict glycemic control in patients with critical limb ischemia. PMID:23509730

Lévigne, D; Tobalem, M; Modarressi, A; Pittet-Cuénod, B

2013-01-01

393

Microbubbles for Thrombolysis of Acute Ischemic Stroke  

Microsoft Academic Search

Improved treatment of acute ischemic stroke with ultrasound and microbubbles in combination with thrombolytic drugs shows great promise, but the optimal techniques, indications, and contraindications have not yet been well defined. Moreover, details such as microbubble dosage, delivery, required thrombolytic drug dosage, and optimal ultrasound characteristics all remain uncertain. Recent results suggest that ultrasound and microbubbles may be effective in

Stephen Meairs; William Culp

2009-01-01

394

CT fogging effect with ischemic cerebral infarcts  

Microsoft Academic Search

Systematic CT studies on ten patients with persistent ischemic cerebral infarct revealed a constant phenomenon, the fogging effect. The hypodense infarct at the beginning will be isodense, or close to isodense, on the plain CT during the second or third weeks and at a later stage will be hypodense again. The fogging infarcted area shows homogeneous intensive contrast enhancement. Knowledge

H. Becker; H. Desch; H. Hacker; A. Pencz

1979-01-01

395

Inflammatory mechanisms in ischemic stroke: therapeutic approaches  

Microsoft Academic Search

Acute ischemic stroke is the third leading cause of death in industrialized countries and the most frequent cause of permanent disability in adults worldwide. Despite advances in the understanding of the pathophysiology of cerebral ischemia, therapeutic options remain limited. Only recombinant tissue-plasminogen activator (rt-PA) for thrombolysis is currently approved for use in the treatment of this devastating disease. However, its

Shaheen E Lakhan; Annette Kirchgessner; Magdalena Hofer

2009-01-01

396

Nitroglycerine and sodium trioxodinitrate: from the discovery to the preconditioning effect.  

PubMed

The history began in the 19th century with Ascanio Sobrero (1812-1888), the discoverer of glycerol trinitrate (nitroglycerine, NTG), and with Angelo Angeli (1864-1931), the discoverer of sodium trioxodinitrate (Angeli's salt). It is likely that Angeli and Sobrero never met, but their two histories will join each other more than a century later. In fact, it has been discovered that both NTG and Angeli's salt are able to induce a preconditioning effect. As NTG has a long history as an antianginal drug its newly discovered property as a preconditioning agent has also been tested in humans. Angeli's salt properties as a preconditioning and inotropic agent have only been tested in animals so far. PMID:23695182

Pagliaro, Pasquale; Gattullo, Donatella; Penna, Claudia

2013-10-01

397

Incomplete Gaussian elimination as a preconditioning for generalized conjugate gradient acceleration  

SciTech Connect

This paper discusses the application of preconditioned generalized conjugate gradient acceleration to fully implicit thermal simulation. The preconditioning step utilizes incomplete Gaussian elimination (IGE) to form an approximate factorization of the Jacobian matrix. IGE preconditioning and its implementation is discussed with respect to five, seven, nine or eleven-point finite difference approximations and optional well constraint equations. Numerical results were obtained using a thermal model allowing any number N/SUB c/ of components. The model's implicit formulation requires the solution of a linear system of equations in which each grid block has N /SUB c/ + 1 unknowns. Test problems involved combustion, steam drive and cyclic steam stimulation processes, some of which exhibited ill-conditioning, negative transmissabilities and high transmissability ratios. Numerical results indicate how different grid block orderings, different levels of incomplete factorization and different acceleration procedures affect convergence, storage and work requirements.

Wallis, J.R.

1983-11-01

398

Cerebrospinal fluid may mediate CNS ischemic injury  

PubMed Central

Background The central nervous system (CNS) is extremely vulnerable to ischemic injury. The details underlying this susceptibility are not completely understood. Since the CNS is surrounded by cerebrospinal fluid (CSF) that contains a low concentration of plasma protein, we examined the effect of changing the CSF in the evolution of CNS injury during ischemic insult. Methods Lumbar spinal cord ischemia was induced in rabbits by cross-clamping the descending abdominal aorta for 1 h, 2 h or 3 h followed by 7 d of reperfusion. Prior to ischemia, rabbits were subjected to the following procedures; 1) CSF depletion, 2) CSF replenishment at 0 mmHg intracranial pressure (ICP), and 3) replacement of CSF with 8% albumin- or 1% gelatin-modified artificial CSF, respectively. Motor function of the hind limbs and histopathological changes of the spinal cord were scored. Post-ischemic microcirculation of the spinal cord was visualized by fluorescein isothiocyanate (FITC) albumin. Results The severity of histopathological damage paralleled the neurological deficit scores. Paraplegia and associated histopathological changes were accompanied by a clear post-ischemic deficit in blood perfusion. Spinal cord ischemia for 1 h resulted in permanent paraplegia in the control group. Depletion of the CSF significantly prevented paraplegia. CSF replenishment with the ICP reduced to 0 mmHg, did not prevent paraplegia. Replacement of CSF with albumin- or gelatin-modified artificial CSF prevented paraplegia in rabbits even when the ICP was maintained at 10–15 mmHg. Conclusion We conclude that the presence of normal CSF may contribute to the vulnerability of the spinal cord to ischemic injury. Depletion of the CSF or replacement of the CSF with an albumin- or gelatin-modified artificial CSF can be neuroprotective. PMID:16174300

Wang, Yanming F; Gwathmey, Judith K; Zhang, Guorong; Soriano, Sulpicio G; He, Shunli; Wang, Yanguang

2005-01-01

399

Sensory Stimulation as a Precondition for the Learning of a Language Task by Fourth and Sixth Grade Children.  

ERIC Educational Resources Information Center

This study was designed to explore learning behavior of children following four specific preconditioning experiences: sensory deprivation, sensory bombardment, routine worksheet exercises, and a sensory awareness game. The study occurred in three parts: preconditioning of the subjects, teaching of a language skill, and performance of a task…

March, Lester William

400

Effects of condition number on preconditioning for low Mach number flows  

NASA Astrophysics Data System (ADS)

The effects of the condition number on convergence characteristics and solution quality for the preconditioned Navier-Stokes equations are studied. A general approach to the construction of preconditioning parameters is proposed to account for the effects of the condition number on these parameters. To verify this technique, laminar flows past a circular cylinder at Reynolds numbers of 20 and 40, and laminar flows past a NACA0012 airfoil at Reynolds numbers of 2500 and 5000 are solved. It is shown that the condition number has effects on the convergence characteristics and solution qualities, and also that a condition number exists that optimizes the convergence characteristics and solution quality.

Lee, Sang-Hyeon

2012-05-01

401

Preconditioning matrices for the pseudospectral approximation of first-order operators  

NASA Technical Reports Server (NTRS)

The behavior of the eigenvalues of preconditioning matrices for the pseudospectral approximation to the derivative operator has been analyzed in one and two dimensions. The one-dimensional analysis resulted in real and positive eigenvalues for the selected tridiagonal matrices. In the two-dimensional analysis, the eigenvalues of the selected block-diagonal matrices behaved well, but the preconditioner is full and therefore not suitable for applications. The Richardson scheme has been applied in the unpreconditioned as well as the preconditioned version to find the solution of the model problem.

Funaro, D.; Rothman, E.

1989-01-01

402

PRECONDITIONED BI-CONJUGATE GRADIENT METHOD FOR RADIATIVE TRANSFER IN SPHERICAL MEDIA  

SciTech Connect

A robust numerical method called the Preconditioned Bi-Conjugate Gradient (Pre-BiCG) method is proposed for the solution of the radiative transfer equation in spherical geometry. A variant of this method called Stabilized Preconditioned Bi-Conjugate Gradient (Pre-BiCG-STAB) is also presented. These are iterative methods based on the construction of a set of bi-orthogonal vectors. The application of the Pre-BiCG method in some benchmark tests shows that the method is quite versatile, and can handle difficult problems that may arise in astrophysical radiative transfer theory.

Anusha, L. S.; Nagendra, K. N. [Indian Institute of Astrophysics, Koramangala, Bangalore 560 034 (India); Paletou, F.; Leger, L. [Laboratoire d'Astrophysique de Toulouse-Tarbes, Universite de Toulouse, CNRS, 14 Ave. E. Belin, 31400 Toulouse (France)

2009-10-10

403

Voice-over-Internet protocol (VoIP) Curriculum Module  

NSDL National Science Digital Library

This curriculum module, created by Dr. Mona Cherri at North Lake College and published by the Convergence Technology Center, presents this module of information about Voice-over-Internet protocol (VoIP) for telecommunications technology and information systems courses. Here, Dr. Cherri has broken the material into five parts: Background Information, VoIP versus public switched telephone networks (PSTNs), VoIP Applications and Services, References, and Useful URLs.

Cherri, Mona

2008-10-27

404

A Mobile Multimedia Communication Framework for IP based Convergence Networks  

Microsoft Academic Search

We propose an efficient mobile multimedia communication protocol, mobile terminal software platform and mobile VoIP application for IP-based convergence networks. The proposed mobile multimedia communication protocol is called as ST-MRSVP (split tunnel based mobile resource reservation protocol) which integrates split tunnel based mobile IP and RSVP. Since mobile multimedia terminal platform should support seamless QoS level, mobile QoS modules for

Won-Tae Kim

2006-01-01

405

Constraint-based watermarking techniques for design IP protection  

Microsoft Academic Search

Digital system designs are the product of valuable ef- fort and know-how. Their embodiments, from software and hard- ware description language program down to device-level netlist and mask data, represent carefully guarded intellectual property (IP). Hence, design methodologies based on IP reuse require new mechanisms to protect the rights of IP producers and owners. This paper establishes principles of watermarking-based

Andrew B. Kahng; John Lach; William H. Mangione-smith; Stefanus Mantik; Igor L. Markov; Miodrag Potkonjak; Paul Tucker; Huijuan Wang; Gregory Wolfe

2001-01-01

406

Network management of TCP\\/IP networks: present and future  

Microsoft Academic Search

Recent network management activities in the TCP\\/IP community have focused on standardizing two network management protocols-Simple Network Management Protocol (SNMP) and Common Management Information Services and Protocol Over TCP\\/IP (CMOT)-that provide for the exchange of management information. The current SNMP and CMOT approaches to TCP\\/IP network management are compared from several different perspectives; comparisons are based on both theory and

Amatzia Ben-Artzi; Asheem Chandna; Unni Warrier

1990-01-01

407

Full TCP\\/IP for 8-bit architectures  

Microsoft Academic Search

We describe two small and portable TCP\\/IP implementations fulfilling the subset of RFC1122 requirements needed for full host-to-host interoperability. Our TCP\\/IP implementations do not sacrifice any of TCP's mechanisms such as urgent data or congestion control. They support IP fragment reassembly and the number of multiple simultaneous connections is limited only by the available RAM. Despite being small and simple,

Adam Dunkels

2003-01-01

408

Application of mobile-IP to space and aeronautical networks  

Microsoft Academic Search

NASA is interested in applying Mobile Internet Protocol (mobile-IP) technologies to its space and aeronautics programs. In particular, mobile-IP will play a major role in the Advanced Aeronautic Transportation Technology (AATT), the Weather Information Communication (WINCOMM) and the Small Aircraft Transportation System; (SATS) aeronautics programs. This paper describes mobile-IP and mobile-routers-in particular, the features, capabilities, and initial performance of the

Kent Leung; Dan Shell; William D. Ivancic; David H. Stewart; Terry L. Bell; B. A. Kachmar

2001-01-01

409

Improved cardiac metabolism and activation of the RISK pathway contributes to improved post-ischemic recovery in calorie restricted mice.  

PubMed

Recent evidence has suggested that activation of AMP-activated protein kinase (AMPK) induced by short-term caloric restriction (CR) protects against myocardial ischemia-reperfusion (I/R) injury. Because AMPK plays a central role in regulating energy metabolism, we investigated whether alterations in cardiac energy metabolism contribute to the cardioprotective effects induced by CR. Hearts from control or short-term CR mice were subjected to ex vivo I/R and metabolism, as well as post-ischemic functional recovery was measured. Even in the presence of elevated levels of fatty acids, CR significantly improved recovery of cardiac function following ischemia. While rates of fatty acid oxidation or glycolysis from exogenous glucose were similar between groups, improved functional recovery post-ischemia in CR hearts was associated with high rates of glucose oxidation during reperfusion compared to controls. Consistent with CR improving energy supply, hearts from CR mice had increased ATP levels, as well as lower AMPK activity at the end of reperfusion compared to controls. Furthermore, in agreement with the emerging concept that CR is a non-conventional form of pre-conditioning, we observed a significant increase in phosphorylation of Akt and Erk1/2 at the end of reperfusion. These data also suggest that activation of the reperfusion salvage kinase (RISK) pathway also contributes to the beneficial effects of CR in reducing post-ischemia contractile dysfunction. These findings also suggest that short-term CR improves post-ischemic recovery by promoting glucose oxidation, and activating the RISK pathway. As such, pre-operative CR may be a clinically relevant strategy for increasing ischemic tolerance of the heart. PMID:21140129

Sung, Miranda M Y; Soltys, Carrie-Lynn M; Masson, Grant; Boisvenue, Jamie J; Dyck, Jason R B

2011-03-01

410

Distinct iPS Cells Show Different Cardiac Differentiation Efficiency  

PubMed Central

Patient-specific induced pluripotent stem (iPS) cells can be generated by introducing transcription factors that are highly expressed in embryonic stem (ES) cells into somatic cells. This opens up new possibilities for cell transplantation-based regenerative medicine by overcoming the ethical issues and immunological problems associated with ES cells. Despite the development of various methods for the generation of iPS cells that have resulted in increased efficiency, safety, and general versatility, it remains unknown which types of iPS cells are suitable for clinical use. Therefore, the aims of the present study were to assess (1) the differentiation potential, time course, and efficiency of different types of iPS cell lines to differentiate into cardiomyocytes in vitro and (2) the properties of the iPS cell-derived cardiomyocytes. We found that high-quality iPS cells exhibited better cardiomyocyte differentiation in terms of the time course and efficiency of differentiation than low-quality iPS cells, which hardly ever differentiated into cardiomyocytes. Because of the different properties of the various iPS cell lines such as cardiac differentiation efficiency and potential safety hazards, newly established iPS cell lines must be characterized prior to their use in cardiac regenerative medicine. PMID:24367382

Yuasa, Shinsuke; Egashira, Toru; Seki, Tomohisa; Hashimoto, Hisayuki; Shimoji, Kenichiro; Kageyama, Toshimi; Tanaka, Tomofumi; Hattori, Fumiyuki; Murata, Mitsushige; Kimura, Kensuke; Fukuda, Keiichi

2013-01-01

411

Lessons Learned in the Design and Use of IP1 / IP2 Flexible Packaging - 13621  

SciTech Connect

For many years in the USA, Low Level Radioactive Waste (LLW), contaminated soils and construction debris, have been transported, interim stored, and disposed of, using IP1 / IP2 metal containers. The performance of these containers has been more than adequate, with few safety occurrences. The containers are used under the regulatory oversight of the US Department of Transportation (DOT), 49 Code of Federal Regulations (CFR). In the late 90's the introduction of flexible packaging for the transport, storage, and disposal of low level contaminated soils and construction debris was introduced. The development of flexible packaging came out of a need for a more cost effective package, for the large volumes of waste generated by the decommissioning of many of the US Department of Energy (DOE) legacy sites across the US. Flexible packaging had to be designed to handle a wide array of waste streams, including soil, gravel, construction debris, and fine particulate dust migration. The design also had to meet all of the IP1 requirements under 49CFR 173.410, and be robust enough to pass the IP2 testing 49 CFR 173.465 required for many LLW shipments. Tens of thousands of flexible packages have been safely deployed and used across the US nuclear industry as well as for hazardous non-radioactive applications, with no recorded release of radioactive materials. To ensure that flexible packages are designed properly, the manufacturer must use lessons learned over the years, and the tests performed to provide evidence that these packages are suitable for transporting low level radioactive wastes. The design and testing of flexible packaging for LLW, VLLW and other hazardous waste streams must be as strict and stringent as the design and testing of metal containers. The design should take into consideration the materials being loaded into the package, and should incorporate the right materials, and manufacturing methods, to provide a quality, safe product. Flexible packaging can be shown to meet the criteria for safe and fit for purpose packaging, by meeting the US DOT regulations, and the IAEA Standards for IP-1 and IP-2 including leak tightness. (authors)

Sanchez, Mike [VP Global Sales, PacTec, Inc. (United States)] [VP Global Sales, PacTec, Inc. (United States); Reeves, Wendall [National Sales Manager, PacTec, Inc. (United States)] [National Sales Manager, PacTec, Inc. (United States); Smart, Bill [Nuclear Sales Director, PacTec, Inc. (United States)] [Nuclear Sales Director, PacTec, Inc. (United States)

2013-07-01

412

Telemetry and Communication IP Video Player  

NASA Technical Reports Server (NTRS)

Aegis Video Player is the name of the video over IP system for the Telemetry and Communications group of the Launch Services Program. Aegis' purpose is to display video streamed over a network connection to be viewed during launches. To accomplish this task, a VLC ActiveX plug-in was used in C# to provide the basic capabilities of video streaming. The program was then customized to be used during launches. The VLC plug-in can be configured programmatically to display a single stream, but for this project multiple streams needed to be accessed. To accomplish this, an easy to use, informative menu system was added to the program to enable users to quickly switch between videos. Other features were added to make the player more useful, such as watching multiple videos and watching a video in full screen.

OFarrell, Zachary L.

2011-01-01

413

Telomere Reprogramming and Maintenance in Porcine iPS Cells  

PubMed Central

Telomere reprogramming and silencing of exogenous genes have been demonstrated in mouse and human induced pluripotent stem cells (iPS cells). Pigs have the potential to provide xenotransplant for humans, and to model and test human diseases. We investigated the telomere length and maintenance in porcine iPS cells generated and cultured under various conditions. Telomere lengths vary among different porcine iPS cell lines, some with telomere elongation and maintenance, and others telomere shortening. Porcine iPS cells with sufficient telomere length maintenance show the ability to differentiate in vivo by teratoma formation test. IPS cells with short or dysfunctional telomeres exhibit reduced ability to form teratomas. Moreover, insufficient telomerase and incomplete telomere reprogramming and/or maintenance link to sustained activation of exogenous genes in porcine iPS cells. In contrast, porcine iPS cells with reduced expression of exogenous genes or partial exogene silencing exhibit insufficient activation of endogenous pluripotent genes and telomerase genes, accompanied by telomere shortening with increasing passages. Moreover, telomere doublets, telomere sister chromatid exchanges and t-circles that presumably are involved in telomere lengthening by recombination also are found in porcine iPS cells. These data suggest that both telomerase-dependent and telomerase-independent mechanisms are involved in telomere reprogramming during induction and passages of porcine iPS cells, but these are insufficient, resulting in increased telomere damage and shortening, and chromosomal instability. Active exogenes might compensate for insufficient activation of endogenous genes and incomplete telomere reprogramming and maintenance of porcine iPS cells. Further understanding of telomere reprogramming and maintenance may help improve the quality of porcine iPS cells. PMID:24098638

Ji, Guangzhen; Ruan, Weimin; Liu, Kai; Wang, Fang; Sakellariou, Despoina; Chen, Jijun; Yang, Yang; Okuka, Maja; Han, Jianyong; Liu, Zhonghua; Lai, Liangxue; Gagos, Sarantis; Xiao, Lei; Deng, Hongkui; Li, Ning; Liu, Lin

2013-01-01

414

( S )-(+)-Ipsdienol: Interspecific inhibition of Ips latidens (leconte) by Ips pini (Say) (Coleoptera: Scolytidae)  

Microsoft Academic Search

In south-central British Columbia, the attraction ofIps latidens (LeConte) to its pheromone, ipsenol, was inhibited by (S)-(+)-ipsdienol, a pheromone forI. pini (Say). (R)-(-)-lpsdienol had no effect onI. latidens. (S)-(+)-lpsdienol probably plays a role in interspecific communication between the two species, facilitating reductions in interspecific competition for breeding material and\\/or interspecific mating interference.

Daniel R. Miller; John H. Borden

1992-01-01

415

The Nonsingularity of Sparse Approximate Inverse Preconditioning and Its Performance Based on Processor Virtualization  

Microsoft Academic Search

In this paper, we analyze the properties of the sparse approximate inverse precon- ditioner, and prove that for a strictly diagonally dominant M matrix, the computed preconditioning matrix can be guaranteed to be nonsingular if it is nonnegative. Then we investigate the use of the processor virtualization technique to parallelize the sparse approximate inverse solver. Numerical experiments on a distributed

Kai Wangy; Orion Lawlor; Laxmikant V. Kale

416

A Comparative Study on Dynamic and Static Sparsity Patterns in Parallel Sparse Approximate Inverse Preconditioning  

Microsoft Academic Search

Sparse approximate inverse (SAI) techniques have recently emerged as a new classof parallel preconditioning techniques for solving large sparse linear systems on highperformance computers. The choice of the sparsity pattern of the SAI matrix is probablythe most important step in constructing an SAI preconditioner. Both dynamicand static sparsity pattern selection approaches have been proposed by researchers.

Kai Wang; Sangbae Kim; Jun Zhang

2003-01-01

417

An efficient preconditioning scheme for real-fluid mixtures using primitive pressure-temperature variables  

Microsoft Academic Search

An improved preconditioning scheme incorporating a unified treatment of general fluid thermodynamics is developed for treating fluid flows over the entire regime of fluid thermodynamic states at all speeds. All of the thermodynamic and numerical properties (such as eigenvalues and Jacobian matrices) are derived directly from fundamental thermodynamics theories, rendering a self- consistent and robust algorithm. Further efficiency is obtained

Nan Zong; Vigor Yang

2007-01-01

418

An M-step preconditioned conjugate gradient method for parallel computation  

NASA Technical Reports Server (NTRS)

This paper describes a preconditioned conjugate gradient method that can be effectively implemented on both vector machines and parallel arrays to solve sparse symmetric and positive definite systems of linear equations. The implementation on the CYBER 203/205 and on the Finite Element Machine is discussed and results obtained using the method on these machines are given.

Adams, L.

1983-01-01

419

Early Pliocene increase in thermohaline overturning: A precondition for the development of the modern equatorial Pacific  

E-print Network

], the modern Northern Hemisphere ice cap was absent, and sea level was 25 m higher than today [e.g., Raymo etClick Here for Full Article Early Pliocene increase in thermohaline overturning: A precondition Atlantic meridional overturning circulation between 4.8 and 4.0 million years ago, initiated

Gilli, Adrian

420

PURDUE EXTENSIONManagingYour Beef Herd: Highlighting Key Determinants of Success in Preconditioning PURDUE EXTENSION  

E-print Network

1 PURDUE EXTENSIONManagingYour Beef Herd: Highlighting Key Determinants of Success in Preconditioning ID-446-W PURDUE EXTENSION Managing Your Beef Herd: Highlighting Key Determinants of Success from a bunk and drink from a fountain/tank. Many PC programs encompass a beef quality assurance

421

Preconditioned conjugate gradient based fast computation of indirect decision feedback equalizer  

Microsoft Academic Search

We use the preconditioned conjugate gradient (PCG) method to compute rapidly the tap weights of a minimum mean-square error (MMSE) decision feedback equalizer (DFE). The equalizer setting is computed indirectly after channel estimation. According to the Toeplitz block structure of the MMSE DFE equation, Rw=r (R is the system matrix), the preconditioner, P, is chosen to be a block diagonal

Peilu Ding; Michael D. Zoltowski; Mark Fimoff

2004-01-01

422

Towards a Sustainable FTAA: DOes Latin America Meet the Necessary Financial Preconditions?  

Microsoft Academic Search

This paper focuses on identifying preconditions that will ensure the sustainability of a Free Trade Area of the Americas (FTAA). It argues that the macro, micro, and political conditions advanced in the literature to measure a country's ability to compete internationally, while necessary, are not sufficient to ensure the success and permanence of a free trade agreement. Instead, two additional

Liliana Rojas-Suarez

2002-01-01

423

Toward a Sustainable FTAA: Does Latin America Meet the Necessary Financial Preconditions?  

Microsoft Academic Search

This paper focuses on identifying preconditions that will ensure the sustainability of a Free Trade Area of the Americas (FTAA). It argues that the macro, micro, and political conditions advanced in the literature to measure a country's ability to compete internationally, while necessary, are not sufficient to ensure the success and permanence of a free trade agreement. Instead, two additional

Liliana Rojas-Suarez

2002-01-01

424

The Role of Macrophage Migration Inhibitory Factor in Anesthetic-Induced Myocardial Preconditioning  

PubMed Central

Introduction Anesthetic-induced preconditioning (AIP) is known to elicit cardioprotective effects that are mediated at least in part by activation of the kinases AMPK and PKC? as well as by inhibition of JNK. Recent data demonstrated that the pleiotropic cytokine macrophage migration inhibitory factor (MIF) provides cardioprotection through activation and/or inhibition of kinases that are also known to mediate effects of AIP. Therefore, we hypothesized that MIF could play a key role in the AIP response. Methods Cardiomyocytes were isolated from rats and subjected to isoflurane preconditioning (4 h; 1.5 vol. %). Subsequently, MIF secretion and alterations in the activation levels of protective kinases were compared to a control group that was exposed to ambient air conditions. MIF secretion was quantified by ELISA and AIP-induced activation of protein kinases was assessed by Western blotting of cardiomyocyte lysates after isoflurane treatment. Results In cardiomyocytes, preconditioning with isoflurane resulted in a significantly elevated secretion of MIF that followed a biphasic behavior (30 min vs. baseline: p?=?0.020; 24 h vs. baseline p?=?0.000). Moreover, quantitative polymerase chain reaction demonstrated a significant increase in MIF mRNA expression 8 h after AIP. Of note, activation of AMPK and PKC? coincided with the observed peaks in MIF secretion and differed significantly from baseline. Conclusions These results suggest that the pleiotropic mediator MIF is involved in anesthetic-induced preconditioning of cardiomyocytes through stimulation of the protective kinases AMPK and PKC?. PMID:24667295

Rossaint, Rolf; Bleilevens, Christian; Dollo, Florian; Siry, Laura; Rajabi-Alampour, Setareh; Beckers, Christian; Soppert, Josefin; Lue, Hongqi; Rex, Steffen; Bernhagen, Jurgen; Stoppe, Christian

2014-01-01

425

A New Class of Parallel Two-level Nonlinear Schwarz Preconditioned Inexact Newton  

E-print Network

. Key words: Incompressible Navier-Stokes equations; multilevel nonlinear preconditioning; inexact is to solve large, sparse, nonlinear systems of equations arising from the discretization of incompressible. Let F(x ) = 0 (1.1) be a nonlinear system of equations and x(0) a given initial guess. Assume x

Cai, Xiao-Chuan

426

Intermittent aortic crossclamping prevents cumulative adenosine triphosphate depletion, ventricular fibrillation, and dysfunction (stunning): Is it preconditioning?  

Microsoft Academic Search

This study was designed to determine whether intermittent warm aortic crossclamping induces cumulative myocardial stunning or if the myocardium becomes preconditioned after the first episode of ischemia in canine models in vivo. The role of adenosine triphosphate catabolism and subsequent release of purines on reperfusion-mediated postischemic ventricular dysfunction and arrhythmias was assessed with the use of selective inhibitors of nucleoside

Anwar S. Abd-Elfattah; Mai Ding; Andrew S. Wechsler

1995-01-01

427

Cognitive Preconditions of Early Reading and Spelling: A Latent-Variable Approach with Longitudinal Data  

ERIC Educational Resources Information Center

The aim of the present study was to empirically disentangle the interdependencies of the impact of nonverbal intelligence, working memory capacities, and phonological processing skills on early reading decoding and spelling within a latent variable approach. In a sample of 127 children, these cognitive preconditions were assessed before the onset…

Preßler, Anna-Lena; Könen, Tanja; Hasselhorn, Marcus; Krajewski, Kristin

2014-01-01

428

Analysis of the retinal gene expression profile after hypoxic preconditioning identifies candidate genes for neuroprotection  

Microsoft Academic Search

BACKGROUND: Retinal degeneration is a main cause of blindness in humans. Neuroprotective therapies may be used to rescue retinal cells and preserve vision. Hypoxic preconditioning stabilizes the transcription factor HIF-1? in the retina and strongly protects photoreceptors in an animal model of light-induced retinal degeneration. To address the molecular mechanisms of the protection, we analyzed the transcriptome of the hypoxic

Markus Thiersch; Wolfgang Raffelsberger; Rico Frigg; Marijana Samardzija; Andreas Wenzel; Olivier Poch; Christian Grimm

2008-01-01

429

Restoration of rocky slopes based on planted gabions and use of drought-preconditioned woody species  

Microsoft Academic Search

The restoration of steep rock faces with shrubs and trees is difficult due to extreme microclimatic and edaphic conditions. In this study, we tested the applicability of free-standing planted gabions to improve the landscape and achieve protection against rockfall, erosion and enhanced surface flow. Furthermore, we analyzed the effect of preconditioning on drought tolerance of several planted species (Ligustrum vulgare,

Barbara Beikircher; Florin Florineth; Stefan Mayr

2010-01-01

430

Ventricular tachycardia in ischemic heart disease substrates  

PubMed Central

Advances in the treatment of myocardial infarction (MI) have improved survival after ischemic cardiac injury. Post-infarct structural and functional remodeling results in electrophysiologic substrates at risk for monomorphic ventricular tachycardia (MMVT). Characterization of this substrate using a variety of clinical and investigative tools has improved our understanding of MMVT circuits, and has accelerated the development of device and catheter-based therapies aimed at identification and elimination of this arrhythmia. This review will discuss the central role of the ischemic heart disease substrate in the development MMVT. Electrophysiologic characterization of the post-infarct myocardium using bipolar electrogram amplitudes to delineate scar border zones will be reviewed. Functional electrogram determinants of reentrant circuits such as isolated late potentials will be discussed. Strategies for catheter ablation of reentrant ventricular tachycardia, including structural and functional targets will also be examined, as will the role of the epicardial mapping and ablation in the management of recurrent MMVT. PMID:24568826

Ajijola, Olujimi A.; Tung, Roderick; Shivkumar, Kalyanam

2014-01-01

431

Aspirin resistant patients with recent ischemic stroke.  

PubMed

Some patients with a recent ischemic stroke who are being treated with aspirin as an antiaggregant suffer a new ischemic stroke. These patients (15-25%) have been called unresponsive to aspirin or aspirin resistant. The aspirin-resistant patients have a four-time greater risk of suffering a stroke. Furthermore, these strokes are generally more severe, with increased infarct volume and greater risk of recurrence. There is currently no ideal laboratory test to detect the resistance to the antiaggregant effect of aspirin. The study of resistance to aspirin would only be indicated in selected cases. In these patients, one should first rule out any "pseudo-resistance" to aspirin (lack of compliance, concomitant treatments that interfere with the action of the aspirin). PMID:24211052

Castilla-Guerra, L; Navas-Alcántara, M S; Fernández-Moreno, M C

2014-04-01

432

Neuroprotective agents in acute ischemic stroke.  

PubMed

The concept of neuroprotection relies on the principle that delayed neuronal injury occurs after ischemia. The phenomenon of the "ischemic cascade" has been described, and each step along this cascade provides a target for therapeutic intervention. A wide variety of drugs have been studied in humans. Ten classes of neuroprotective agents have reached phase III efficacy trials but have shown mixed results. They included calcium channel antagonists, NMDA receptor antagonists, lubeluzole, CDP-choline, the free radical scavenger tirilazad and ebselen, enlimomab, GABA agonist clomethiazole, the sodium channel antagonist fosphenytoin, magnesium, glycine site antagonist GV150526 and piracetam. Furthermore, the mechanisms that underlie the development of focal ischemic injury continue to be discovered, opening new therapeutic perspective for neuroprotection that might clinically be applicable in the future. PMID:12038658

Sareen, D

2002-02-01

433

Heart failure in acute ischemic stroke  

Microsoft Academic Search

Background\\u000a   To determine\\u000a the impact of heart failure\\u000a (HF), with preserved or decreased\\u000a left ventricular function (LVF), on\\u000a outcome in patients with acute\\u000a ischemic stroke (AIS).\\u000a \\u000a \\u000a \\u000a \\u000a Methods\\u000a   We\\u000a studied 503 unselected ischemic\\u000a stroke patients. Poor outcome was\\u000a defined as moderate-severe disability\\u000a or death at 90 days. We analyzed\\u000a the association between poor outcome\\u000a and HF with preserved LVF\\u000a or decreased

A. Ois; M. Gomis; E. Cuadrado-Godia; J. Jiménez-Conde; A. RodrÍguez-Campello; J. Bruguera; L. Molina; J. Comin; J. Roquer

2008-01-01

434

Compositional Control of IP Media Pamela Zave and Eric Cheung  

E-print Network

and significance of application servers depends on several aspects of the architecture of media services1 Compositional Control of IP Media Pamela Zave and Eric Cheung AT&T Laboratories--Research, Florham Park, New Jersey USA pamela,cheung@research.att.com Abstract-- In many IP media services

Fisher, Kathleen

435

A Hybrid Genetic Algorithm for Routing Optimization in IP Networks  

E-print Network

engineering are demonstrated. Keywords ­ IP Traffic engineering, genetic algorithm, bandwidth-delay sensitiveA Hybrid Genetic Algorithm for Routing Optimization in IP Networks Utilizing Bandwidth and Delay traffic engineering, which relies on conventional, destination-based routing protocols. We introduce

Riedl, Anton

436

Managing Best Effort IP Networks over Heterogeneous WANs  

Microsoft Academic Search

While corporate networks are predominantly TCP\\/IP, the underlying technology used to interconnect an organization's network varies widely. Technologies include private TDM lines, frame relay, ATM and IP. Each technology requires its own network management technique. The problem of correlating low level WAN measures to application performance is difficult, especially if multiple WAN service providers are involved each with their own

Jim Martin

437

IP design of universal multiple devices SPI interface  

Microsoft Academic Search

The implementation and feature of the standard SPI protocol are analyzed. Based on the Standard SPI protocol, the SPI interface IP for multiple devices is designed by Parameterization method. The communication among multiple devices with the IP is fully complied with the Standard SPI protocol. And it could automatically identify the master\\/slave devices and accomplish that multi-master devices could use

Tianxiang Liu; Yunfeng Wang

2011-01-01

438

Scheduling algorithms for input-queued IP routers  

E-print Network

1 1 Scheduling algorithms for input-queued IP routers Andrea Bianco Paolo Giaccone Gruppo Reti di Architectures 2011/12 2 Outline IP routers OQ routers IQ routers Scheduling Optimal algorithms Heuristic algorithms Packet-mode algorithms Networks of routers QoS support CIOQ routers Multicast traffic Conclusions

Giaccone, Paolo

439

Taming IP Packet Flooding Attacks Karthik Lakshminarayanan Daniel Adkins  

E-print Network

Taming IP Packet Flooding Attacks Karthik Lakshminarayanan Daniel Adkins ¡ Adrian Perrig Ion hosts is denial- of-service (DoS) caused by IP packet floods. Hosts in the Internet are unable to stop ­ not the net- work ­ should be given control to respond to packet floods and overload. Ideally, hosts should

440

Troubleshooting Chronic Conditions in Large IP Networks Ajay Mahimkar  

E-print Network

of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation a diverse set of ap- plications. Many applications, such as Voice over IP (VoIP), Internet television (IPTV

Zhang, Yin

441

Traffic Management for Aggregate IP Streams Alan Chapman  

E-print Network

Traffic Management for Aggregate IP Streams Alan Chapman Nortel Networks P.O.Box 3511, Station C to that used for ATM connections, is suggested for the traffic management of IP aggregates. ATM networks use. An approach that uses TCP's congestion control to manage sharing between aggregated streams of traffic

Kung, H. T.

442

High speed ip address lookup architecture using hashing  

Microsoft Academic Search

One of the most important design issues for IP routers responsible for datagram forwarding in computer networks is the route-lookup mechanism. In this letter, we explore a practical IP address lookup scheme which converts the longest prefix matching problem into the exact matching problem. In the proposed architecture, the forwarding table is composed of multiple SRAM, and each SRAM represents

Hyesook Lim; Ji-Hyun Seo; Yeo-Jin Jung