bluuebunny/crossref_metadata_2025 huggingface dataset:
SHAPE INVARIANCE AND BPS BOUNDS IN ϕ4 AND SINE–GORDON THEORIES
Authors: SADEGHI J. , MOHAMMADI A.
Published: June 2007

In this paper, we identify the deeper structure that produces shape invariance. We show that shape invariance appears when a quantum mechanical model is invariant under a centrally extended superalgebra. Also we show that in Φ4 and sine–Gordon theories, shape invariance arises from the Bogomol'nyi–Prasad–Sommerfeld (BPS) structure associated with shift operator. The shift operator in two models ensures that there is a one-to-one correspondence between the energy levels and energies of the BPS saturating.
MANDELSTAM–LEIBBRANDT: NOT REALLY A PRESCRIPTION IN THE LIGHT-CONE GAUGE
Authors: BENTÍN RICARDO , SUZUKI ALFREDO T.
Published: June 2007

Since the very beginning of it, perhaps the subtlest of all gauges is the light-cone gauge, for its implementation leads to characteristic singularities that require some kind of special prescription to handle them in a proper and consistent manner. The best known of these prescriptions is the Mandelstam–Leibbrandt one. In this work we revisit it showing that its status as a mere prescription is not appropriate but rather that its origin can be traced back to fundamental physical properties such as causality and covariantization methods.
SUM RULES OF FOUR-NEUTRINO MIXING IN MATTER
Authors: ZHANG HE
Published: June 2007

Assuming the existence of one light sterile neutrino, we investigate the neutrino flavor mixing matrix in matter. Sum rules between the mixing parameters in vacuum and their counterparts in matter are derived. By using these new sum rules, we obtain the simple but exact expressions of the effective flavor mixing matrix in matter in terms of neutrino masses and the mixing parameters in vacuum. The rephasing invariants, sides of unitarity quadrangles and oscillation probabilities in matter are also achieved. Our model-independent results will be very helpful for analyzing flavor mixing and CP violation in the future long-baseline neutrino oscillation experiments.
MiniBooNE AND A CP2 = -𝟙 STERILE NEUTRINO
Authors: AHLUWALIA-KHALILOVA D. V. , NIELSEN ALEX B.
Published: June 2007

It has been taken as granted that the observation of two independent mass-squared differences necessarily fixes the number of underlying mass eigenstates as three, and that the addition of a sterile neutrino provides an additional mass-squared difference. The purpose of this letter is to argue that if one considers a sterile neutrino component that belongs to the CP 2 = -𝟙 sector, then both of the stated claims are false. We also outline how the results reported here, when combined with the forthcoming MiniBooNE data and other experiments, can help settle the issue of the CP properties of the sterile neutrino; if such a component does indeed exist.
A NEW MATHEMATICAL MODEL FOR OPTIMAL CONTROL STRATEGIES OF INTEGRATED PEST MANAGEMENT
Authors: MENG XINZHU , SONG ZHITAO , CHEN LANSUN
Published: June 2007

A state-dependent impulsive SI epidemic model for integrated pest management (IPM) is proposed and investigated. We shall examine an optimal impulsive control problem in the management of an epidemic to control a pest population. We introduce a small amount of pathogen into a pest population with the expectation that it will generate an epidemic and that it will subsequently be endemic such that the number of pests is no larger than the given economic threshold (ET), so that the pests cannot cause economic damage. This is the biological control strategy given in the present paper. The combination strategy of pulse capturing (susceptible individuals) and pulse releasing (infective individuals) is implemented in the model if the number of pests (susceptible) reaches the ET. Firstly, the impulsive control problem is to drive the pest population below a given pest level and to do so in a manner which minimizes a weighted sum of the cost of using the control. Hence, for a one time impulsive effect we obtain the optimal strategy in terms of total cost such that the number of pests is no larger than the given ET. Secondly, we show the existence of periodic solution with the number of pests no larger than ET, and by using the Analogue of the Poincaré Criterion we prove that it is asymptotically stable under a planned impulsive control strategy. Further, the period T of the periodic solution is calculated, which can be used to estimate how long the pest population will take to return back to its pre-control level. The main feature of the present paper is to apply an SI infectious disease model to IPM, and some pests control strategies are given.
EFFECT OF DELAY ON THE MODEL OF AMERICAN CUTANEOUS LEISHMANIASIS
Authors: DAS PRASENJIT , MUKHERJEE DEBASIS , SARKAR A. K.
Published: June 2007

This paper investigates the dynamics of transmission of a model of American cutaneous leishmaniasis (ACL). The model consists of infectious incidental hosts (humans), reservoir hosts (forest rodents, dogs, etc.) and vectors. A delay in the time between infection and infectiousness for the reservoir hosts is incorporated. In the absence of delay, it is observed that if R0 > 1, then endemic equilibrium becomes stable and if R0 < 1 then infection-free equilibrium becomes stable. The length of delay is estimated for preserving stability. Stability switching behavior of the system is also indicated. Lastly the results are verified through numerical simulations as far as possible.
ESCAPE THROUGH A FLUCTUATING ENERGY BARRIER IN THE PRESENCE OF NON-GAUSSIAN NOISE
Authors: GOSWAMI GURUPADA , MAJEE PRADIP , BAG BIDHAN CHANDRA
Published: June 2007

In this paper we have studied how barrier crossing dynamics is affected by colored additive non-Gaussian noise if the barrier fluctuates deterministically. Our investigation indicates that resonant activation(RA) is either enhanced or it becomes robust if noise characteristic is deviated from the Gaussian behavior. We find that additive colored non Gaussian noise can induce the RA-like phenomenon. Another interesting observation is that the turnover behavior persists even in presence of barrier fluctuations at finite rate. Finally, it is observed that mean first passage time(MFPT) decreases with increase of non-Gaussian characteristic of the additive colored noise for a given noise strength and noise correlation time and ultimately reaches to a limiting value. The limiting value remains almost the same if the barrier fluctuating frequency is zero or far from the resonant condition. But near the resonant condition the mean first passage time initially decreases and then increases passing through a minimum as the non Gaussian parameter grows.
REVIEW OF FLICKER NOISE SPECTROSCOPY IN ELECTROCHEMISTRY
Authors: TIMASHEV SERGE F. , POLYAKOV YURIY S.
Published: June 2007

This review presents the fundamentals of Flicker-Noise Spectroscopy (FNS), a general phenomenological methodology in which the dynamics and structure of complex systems, characterized by non-linear interactions, dissipation, and inertia, are analyzed by extracting information from various signals with stochastically varying components generated by the systems. The basic idea of FNS is to treat the correlation links present in sequences of different irregularities, such as spikes, "jumps", and discontinuities in derivatives of different orders, on all levels of the spatiotemporal hierarchy of the system under study as main information carriers. The tools to extract and analyze the information are power spectra and difference moments (structural functions) of various orders. Presently, FNS can be applied to three types of problems: (1) determination of parameters or patterns that characterize the dynamics or structural features of complex systems; (2) finding precursors of abrupt changes in the state of various complex systems based on a priori information about the dynamics of the systems; and (3) determination of flow dynamics in distributed systems based on the analysis of dynamic correlations in stochastic signals that are simultaneously measured at different points in space. Examples of FNS applications to such problems as parameterization of the images produced with atomic force microscopy (AFM), determination of precursors for electric breakdowns and major earthquakes, and analysis of electric potential fluctuations in electromembrane systems, as well as to some other problems in electrochemistry and medicine are discussed.
A GROUPING GENETIC ALGORITHM FOR THE MULTIPLE TRAVELING SALESPERSON PROBLEM
Authors: BROWN EVELYN C. , RAGSDALE CLIFF T. , CARTER ARTHUR E.
Published: June 2007

The multiple traveling salesperson problem (MTSP) involves scheduling m > 1 salespersons to visit a set of n > m locations. Thus, the n locations must be divided into m groups and arranged so that each salesperson has an ordered set of cities to visit. The grouping genetic algorithm (GGA) is a type of genetic algorithm (GA) designed particularly for grouping problems. It has been successfully applied to a variety of grouping problems. This paper focuses on the application of a GGA to solve the MTSP. Our GGA introduces a new chromosome representation to indicate which salesperson is assigned to each tour and the ordering of the cities within each tour. We compare our method to standard GAs that employ either the one-chromosome or two-chromosome representation for MTSP. This research demonstrates that our GGA with its new chromosome representation is capable of solving a variety of MTSP problems from the literature and can outperform the traditional encodings of previously published GA methods.
PARALLEL PROCESSING OF OLAP QUERIES USING A CLUSTER OF WORKSTATIONS
Authors: DEHURI S. , MALL R.
Published: June 2007

Online analytical processing (OLAP) queries normally incur enormous processing overheads due to the huge size of data warehouses. This results in unacceptable response times. Parallel processing using a cluster of workstations has of late emerged as a practical solution to many compute and data intensive problems. In this article, we present parallel algorithms for some of the OLAP operators. We have implemented these parallel solutions for a data warehouse implemented on Oracle hosted in a cluster of workstations. Our performance studies show that encouraging speedups are achieved.
THE INCREMENTAL MINING OF CONSTRAINED CUBE GRADIENTS
Authors: LIU YUBAO , FENG JIANLIN , YIN JIAN
Published: June 2007

The mining of cube gradients is an extension of traditional association rules mining in data cube and has broad applications. In this paper, we consider the problem of mining constrained cube gradients for partially materialized data cubes. Its purpose is to extract interesting gradient-probe cell pairs from partially materialized cubes while adding or deleting cells. Instead of directly searching the new data cubes from scratch, an incremental mining algorithm IncA is presented, which sufficiently uses the mined cube gradients from old data cubes. In our algorithms, the condensed cube structure is used to reduce the sizes of materialized cubes. Moreover, some efficient methods are presented in IncA to optimize the comparison process of cell pairs. The performance studies show the incremental mining algorithm IncA is more efficient and scalable than the directed mining algorithm DA with different constraints and sizes of materialized data cubes.
Agent Based Process Management Environment – Mercury
Authors: Kim Jeong Ah , Choi Seung Young , Jung Rhan
Published: June 2007

In this article, agent based process management model is proposed, which is for the process management of knowledge worker and service workers in order to establish the basis for the new knowledge management system. In this article, we applied several methods from 6-Sigma and personal software process for personal process definition, process execution and process measurement. This study attempts to improve the process execution accuracy through process visualisation and standardisation and to accumulate the base data to improve the process through measuring the process execution. We proposed guidelines and detail procedures for developing three advisor agents for guiding the process definition, process execution and process measurement. We showed the simple case study applied our guidelines.
Sexual Selection and Speciation
Authors: Ritchie Michael G.
Published: June 2007

Sexual selection has a reputation as a major cause of speciation, one of the most potent forces driving reproductive isolation. This reputation arises from observations that species differ most in traits involved with mating success and from successful models of sexual selection–driven speciation. But how well proven is the case? Models confirm that the process can occur, but is strongest in conjunction with ecological or niche specialization. Some models also show that strong sexual selection can act against speciation. Studies using the comparative method are equivocal and often inconclusive, but some phylogeographic studies are more convincing. Experimental evolution and genetic or genomic analyses are in their infancy, but look particularly promising for resolving the importance of sexual selection. The case for sexual selection is not as strongly supported as, for example, allopatric speciation. Sexual selection probably contributes most effectively alongside ecological selection or selection for species recognition than as a solitary process.
Evolutionarily conserved WNK and Ste20 kinases are essential for acute volume recovery and survival after hypertonic shrinkage in Caenorhabditis elegans
Authors: Choe Keith P. , Strange Kevin
Published: June 2007

Members of the germinal center kinase (GCK)-VI subfamily of Ste20 kinases regulate a Caenorhabditis elegans ClC anion channel and vertebrate SLC12 cation-Cl− cotransporters. With no lysine (K) (WNK) protein kinases interact with and activate the mammalian GCK-VI kinases proline-alanine-rich Ste20-related kinase (PASK) and oxidative stress-responsive 1 (OSR1). We demonstrate here for the first time that GCK-VI kinases play an essential role in whole animal osmoregulation. RNA interference (RNAi) knockdown of the single C. elegans GCK-VI kinase, GCK-3, dramatically inhibits systemic volume recovery and survival after hypertonic shrinkage. Tissue-specific RNAi suggests that GCK-3 functions primarily in the hypodermis and intestine to mediate volume recovery. The single C. elegans WNK kinase, WNK-1, binds to GCK-3, and wnk-1 knockdown gives rise to a phenotype qualitatively similar to that of gck-3(RNAi) worms. Knockdown of the two kinases together has no additive effect, suggesting that WNK-1 and GCK-3 function in a common pathway. We postulate that WNK-1 functions upstream of GCK-3 in a manner similar to that postulated for its mammalian homologs. Phylogenetic analysis of kinase functional domains suggests that the interaction between GCK-VI and WNK kinases first occurred in an early metazoan and therefore likely coincided with the need of multicellular animals to tightly regulate transepithelial transport processes that mediate systemic osmotic homeostasis.
KGF promotes integrin α5 expression through CCAAT/enhancer-binding protein-β
Authors: Koria Piyush , Andreadis Stelios T.
Published: June 2007

Keratinocyte growth factor (KGF) and α5β1-integrin are not expressed in normal skin but they are both highly upregulated in the migrating epidermis during wound healing. Here we report that KGF increased α5 mRNA and protein levels in epidermoid carcinoma cells and stratified bioengineered epidermis. Interestingly, KGF increased integrin α5 in the basal as well as suprabasal cell epidermal layers. Promoter studies indicated that KGF-induced integrin α5 promoter activation was dependent on the C/EBP transcription factor binding site. Accordingly, KGF induced sustained phosphorylation of C/EBP-β that was dependent on activation of ERK1/2. In addition, a dominant negative form of C/EBP-β inhibited α5 promoter activity and blocking C/EBP-β with siRNA diminished integrin α5 expression. Taken together, our data indicate that KGF increased integrin α5 expression by phosphorylating C/EBP-β. Interestingly, KGF-induced upregulation of integrin α5 was more pronounced in three-dimensional tissue analogues than in conventional two-dimensional culture suggesting that stratified epidermis may be useful in understanding the effects of growth factors in the local tissue microenvironment.
Cadmium-induced ceramide formation triggers calpain-dependent apoptosis in cultured kidney proximal tubule cells
Authors: Lee Wing-Kee , Torchalski Blazej , Thévenod Frank
Published: June 2007

A major target of cadmium (Cd2+) toxicity is the kidney proximal tubule (PT) cell. Cd2+-induced apoptosis of PT cells is mediated by sequential activation of calpains at 3–6 h and caspases-9 and -3 after 24-h exposure. Calpains also partly contribute to caspase activation, which emphasizes the importance of calpains for PT apoptosis by Cd2+. Upstream processes underlying Cd2+-induced calpain activation remain unclear. We describe for the first time that 10–50 μM Cd2+ causes a significant increase in ceramide formation by ∼22% (3 h) and ∼72% (24 h), as measured by diacylglycerol kinase assay. Inhibition of ceramide synthase with fumonisin B1 (3 μM) prevents ceramide formation at 3 h and abolishes calpain activation at 6 h, which is associated with significant attenuation of apoptosis at 3–6 h with Hoechst 33342 nuclear staining and/or 3(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2 H-tetrazolium bromide (MTT) death assays. This indicates that Cd2+ enhances de novo ceramide synthesis and that calpains are a downstream target of ceramides in apoptosis execution. Moreover, addition of C6-ceramide to PT cells increases cytosolic Ca2+ and activates calpains. Apoptosis mediated by C6-ceramide at 24 h is significantly reduced by caspase-3 inhibition, which supports cross talk between calpain- and caspase-dependent apoptotic pathways. We conclude that Cd2+-induced apoptosis of PT cells entails endogenous ceramide elevation and subsequent Ca2+-dependent calpain activation, which propagates kidney damage by Cd2+.
Transmural heterogeneity of diffusion anisotropy in the sheep myocardium characterized by MR diffusion tensor imaging
Authors: Jiang Yi , Guccione Julius M. , Ratcliffe Mark B. , Hsu Edward W.
Published: June 2007

The orientation of MRI-measured diffusion tensor in the myocardium has been directly correlated to the tissue fiber direction and widely characterized. However, the scalar anisotropy indexes have mostly been assumed to be uniform throughout the myocardial wall. The present study examines the fractional anisotropy (FA) as a function of transmural depth and circumferential and longitudinal locations in the normal sheep cardiac left ventricle. Results indicate that FA remains relatively constant from the epicardium to the midwall and then decreases (25.7%) steadily toward the endocardium. The decrease of FA corresponds to 7.9% and 12.9% increases in the secondary and tertiary diffusion tensor diffusivities, respectively. The transmural location of the FA transition coincides with the location where myocardial fibers run exactly circumferentially. There is also a significant difference in the midwall-endocardium FA slope between the septum and the posterior or lateral left ventricular free wall. These findings are consistent with the cellular microstructure from histological studies of the myocardium and suggest a role for MR diffusion tensor imaging in characterization of not only fiber orientation but, also, other tissue parameters, such as the extracellular volume fraction.
Sodium ion concentration vs. sweat rate relationship in humans
Authors: Buono Michael J. , Ball Kimberly D. , Kolkhorst Fred W.
Published: June 2007

The purpose of this study was to determine the effect of active heat acclimation on the sweat osmolality and sweat sodium ion concentration vs. sweat rate relationship in humans. Eight healthy male volunteers completed 10 days of exercise in the heat. The mean exercising heart rate and core temperature were significantly decreased ( P < 0.05) by 18 beats/min and 0.6°C, respectively, following heat acclimation. Furthermore, sweat osmolality and the sweat sodium ion concentration vs. sweat rate relationships were shifted to the right. Specifically, the slopes of the relationships were not affected by heat acclimation. Rather, heat acclimation significantly reduced the y-intercepts of the sweat osmolality and sweat sodium relationships with sweat rate by 28 mosmol/kgH2O and 15 mmol/l, respectively. Thus there was a significantly lower sweat sodium ion concentration for a given sweat rate following heat acclimation. These results suggest that heat acclimation increases the sodium ion reabsorption capacity of the human eccrine sweat gland.
Eccentric exercise increases EMG amplitude and force fluctuations during submaximal contractions of elbow flexor muscles
Authors: Semmler John G. , Tucker Kylie J. , Allen Trevor J. , Proske Uwe
Published: June 2007

The purpose of this study was to determine the effect of eccentric exercise on the ability to exert steady submaximal forces with muscles that cross the elbow joint. Eight subjects performed two tasks requiring isometric contraction of the right elbow flexors: a maximum voluntary contraction (MVC) and a constant-force task at four submaximal target forces (5, 20, 35, 50% MVC) while electromyography (EMG) was recorded from elbow flexor and extensor muscles. These tasks were performed before, after, and 24 h after a period of eccentric (fatigue and muscle damage) or concentric exercise (fatigue only). MVC force declined after eccentric exercise (45% decline) and remained depressed 24 h later (24%), whereas the reduced force after concentric exercise (22%) fully recovered the following day. EMG amplitude during the submaximal contractions increased in all elbow flexor muscles after eccentric exercise, with the greatest change in the biceps brachii at low forces (3–4 times larger at 5 and 20% MVC) and in the brachialis muscle at moderate forces (2 times larger at 35 and 50% MVC). Eccentric exercise resulted in a twofold increase in coactivation of the triceps brachii muscle during all submaximal contractions. Force fluctuations were larger after eccentric exercise, particularly at low forces (3–4 times larger at 5% MVC, 2 times larger at 50% MVC), with a twofold increase in physiological tremor at 8–12 Hz. These data indicate that eccentric exercise results in impaired motor control and altered neural drive to elbow flexor muscles, particularly at low forces, suggesting altered motor unit activation after eccentric exercise.
Quantal and Nonquantal Transmission in Calyx-Bearing Fibers of the Turtle Posterior Crista
Authors: Holt Joseph C. , Chatlani Shilpa , Lysakowski Anna , Goldberg Jay M.
Published: June 2007

Intracellular recordings were made from nerve fibers in the posterior ampullary nerve near the neuroepithelium. Calyx-bearing afferents were identified by their distinctive efferent-mediated responses. Such fibers receive inputs from both type I and type II hair cells. Type II inputs are made by synapses on the outer face of the calyx ending and on the boutons of dimorphic fibers. Quantal activity, consisting of brief mEPSPs, is reduced by lowering the external concentration of Ca2+and blocked by the AMPA-receptor antagonist CNQX. Poisson statistics govern the timing of mEPSPs, which occur at high rates (250–2,500/s) in the absence of mechanical stimulation. Excitation produced by canal-duct indentation can increase mEPSP rates to nearly 5,000/s. As the rate increases, mEPSPs can change from a monophasic depolarization to a biphasic depolarizing–hyperpolarizing sequence, both of whose components are blocked by CNQX. Blockers of voltage-gated currents affect mEPSP size, which is decreased by TTX and is increased by linopirdine. mEPSP size decreases severalfold after impalement. The size decrease, although it may be triggered by the depolarization occurring during impalement, persists even at hyperpolarized membrane potentials. Nonquantal transmission is indicated by shot-noise calculations and by the presence of voltage modulations after quantal activity is abolished pharmacologically. An ultrastructural study shows that inner-face inputs from type I hair cells outnumber outer-face inputs from type II hair cells by an almost 6:1 ratio.
Maternal Plasma Procalcitonin Concentrations in Pregnancy Complicated by Preterm Premature Rupture of Membranes
Authors: Torbé Andrzej
Published: June 2007

Objectives. Our objective is to compare maternal plasma procalcitonin concentrations in preterm premature rupture of membranes (pPROM) and premature rupture of membranes (PROM) at term with their levels in uncomplicated pregnancy, and to determine whether these concentrations are useful in the diagnosis of pPROM cases suspected of infection and in the prediction of pPROM-to-delivery interval. Study design. Forty eight patients with pPROM, 30 with PROM at term, 31 healthy women at preterm gestation, and 33 healthy women at term were included. In pPROM group, analysis of procalcitonin concentrations with reference to leucocytosis, serum C-reactive protein, vaginal fluid culture, neonatal infection, histological chorioamnionitis and pPROM-to-delivery interval was carried out.Results. Procalcitonin concentrations in pPROM and PROM at term cases were comparable. However, in both groups procalcitonin values were significantly higher than in healthy controls in approximate gestational age. In pPROM group, procalcitonin concentrations between the patients with and without laboratory indices of infection were comparable, as well as between patients who gave birth to newborns with and without congenital infection, and between patients with and without histological chorioamnionitis. The predictive values of procalcitonin determinations were poor.Conclusion. The value of maternal plasma procalcitonin determinations in the diagnostics of pPROM cases suspected of intraamniotic infection, as well as for the prediction of pPROM-to-delivery interval, newborn's infection or histological chorioamnionitis is unsatisfactory. However, procalcitonin concentrations are elevated, both in patients with preterm and term PROMs in comparison to healthy pregnants, and therefore further evaluations are necessary to establish the role of procalcitonin in the pathophysiology of pregnancy.
Mild Hyperhomocysteinemia and Low Folate Concentrations as Risk Factors for Cervical Arterial Dissection
Authors: Arauz Antonio , Hoyos Leticia , Cantú Carlos , Jara Aurelio , Martínez Leticia , García Irma , Fernández María de los Ángeles , Alonso Elisa
Published: June 2007

Background and Purpose: Elevated homocysteine (Hcy) plasma levels are associated with an increased risk of spontaneous cervical artery dissection (sCAD). We examined the potential association between Hcy, folate, vitamin B12 levels and 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphisms in patients with cerebral infarct caused by sCAD. Patients and Methods: 39 patients who survived a cerebral infarct caused by sCAD [20 (51%) women; 24 (61.5%) vertebral and 15 (38.5%) internal carotid arteries], and 76 healthy control subjects were included. Hcy plasma levels (fasting and after methionine load), folate and vitamin B12 levels were measured. We also performed polymorphisms of MTHFR. Hcy, vitamin B12, folates and polymorphisms of MTHFR were assessed and any associations were analyzed using multivariate statistics. Results: Mean plasma fasting Hcy level was 9.81 µmol/l for cases and 6.38 for controls (p = 0.001). The occurrence of sCAD was associated with elevated fasting Hcy levels (>95th percentile over the control group) with an adjusted odds ratio of 7.9 (95% CI 1.66–35). The association between low plasma folate values (<5th percentile) and the presence of CAD was 7.9 (95% CI 1.6–31) after adjusting for confounding variables. The distribution of the MTHFR genotype showed a higher TT mutant frequency among CAD patients (p = 0.034). Conclusions: High plasma concentrations of Hcy and low plasma levels of folate were associated with an increased risk of sCAD in the sample studied. We conclude that deficiencies in nutritional status may contribute to the relatively high incidence of CAD in Mexico.
Effect of On-Admission Antiplatelet Treatment on Patients with Cerebral Hemorrhage
Authors: Caso Valeria , Paciaroni Maurizio , Venti Michele , Alberti Andrea , Palmerini Francesco , Milia Paolo , Billeci Antonia M.R. , Silvestrelli Giorgio , Biagini Sergio , Agnelli Giancarlo
Published: June 2007

Background: Antiplatelet treatment remains the first choice for primary and secondary prevention of vascular diseases; even so, expected benefits may be offset by risk of bleeding, particularly cerebral hemorrhage. The aim of this study was to assess the influence of antiplatelet treatment on clinical outcome at hospital discharge. Materials and Methods: Consecutive patients with first-ever stroke due to a primary intraparenchymal hemorrhage were prospectively identified over a 4-year period (2000–2003). Data on hemorrhage location, vascular risk factors, and antiplatelet and anticoagulant treatment were collected. At discharge, outcome was measured using the modified Rankin Scale (disabling stroke ≧3). Patients treated with anticoagulant therapy were excluded from the study. Results: Of 457 consecutive patients with cerebral hemorrhage, 94 (20.5%) had been taking antiplatelet agents. The treated patients (mean age for antiplatelet group 78.9 ± 9.0 years) were older than the nontreated patients (73.8 ± 9.4, p = 0.02). In-hospital mortality was 23.4 and 23.1% (p = n.s.) for patients who had been taking antiplatelet agents or no treatment. Poor outcome at discharge was found in 52.1 and 59.7% (p = n.s.), respectively. Univariate analysis showed that age and coma at admission were predictors of disability at discharge, but antiplatelet treatment was not. Additionally, age and coma were shown to be determinants of disability at discharge after multivariate analysis: OR 1.03 per year (95% CI: 1.018–1.049), p < 0.001 and OR 1.68 (95% CI: 1.138–2.503), p = 0.009, respectively. Conclusions: Hemorrhagic stroke continues to be responsible for a high percentage of disability and death. Furthermore, it was seen here that functional outcome was independent of previous antiplatelet treatment.
Impact of Recombinant Activated Factor VII on Health-Related Quality of Life after Intracerebral Hemorrhage
Authors: Diringer Michael N. , Ferran Jean-Marc , Broderick Joseph , Davis Stephen , Mayer Stephan A. , Steiner Thorsten , Brun Nikolai C. , Skolnick Brett E. , Christensen Michael C.
Published: June 2007

Background: We recently demonstrated that recombinant activated factor VII (rFVIIa) given to patients presenting within 3 h of acute spontaneous intracerebral hemorrhage (ICH) reduces mortality (18% vs. 29%) and poor outcome (modified Rankin Scale, mRS, 4–6, 53 vs. 69%). This analysis was performed to determine the impact of rFVIIa on health-related quality of life (HRQoL) in those patients. Methods: In a prospective, randomized controlled trial, 399 patients (mean age, 66 years) received placebo, 40, 80 or 160 µg/kg of rFVIIa within 4 h of acute ICH. At 90 days, HRQoL was assessed with the EuroQoL (EQ-5D), a 5-dimensional measure of health which also includes the Visual Analogue Scale. Additionally, each level of the 90-day mRS was adjusted, using 4 different previously published utility values, to obtain a clearer picture of perceived HRQoL. Results: Among the 5 dimensions of EQ-5D, only mobility rating was significantly better for rFVIIa-treated patients (serious problems, 34 vs. 54%; p = 0.01). Yet, the utility value (scaled 1.0 = perfect health and 0.0 = dead) associated with the composite EQ-5D demonstrated significantly better HRQoL (0.48 vs. 0.36; p = 0.01). This was also true for the EQ-5D Visual Analogue Scale score (44 vs. 36; p = 0.04). Finally, all 4 algorithms for applying utility scores to the mRS indicated that rFVIIa was associated with significantly better perceived HRQoL (all p < 0.006). Conclusions: Treatment with rFVIIa within 4 h of acute spontaneous ICH improves HRQoL.
Prognostic Value of Myocardial Perfusion Gated SPECT in Patients with Symptomatic Intracranial Large-Artery Atherosclerosis
Authors: Candell-Riera J. , Arenillas J.F. , Romero-Farina G. , Aguadé-Bruix S. , de León G. , Castell-Conesa J. , Molina C.A. , Rovira A. , Álvarez-Sabín J.
Published: June 2007

Background: We aimed to evaluate the prognostic value of myocardial perfusion gated SPECT in patients with symptomatic intracranial large-artery atherosclerosis (ILA). Methods: Seventy-two consecutive first-ever symptomatic ILA patients without known heart disease underwent a stress myocardial perfusion gated SPECT, and long-term follow-up was conducted thereafter. Results: During an average follow-up of 15.2 ± 9 months, 9 patients (13.8%) presented major coronary events (CEs). Survival analyses (Kaplan-Meier and Cox regression) identified presence of moderate-to-severe myocardial perfusion defects (log rank p = 0.004) and ejection fraction <50% (p = 0.014) as predictors of future CEs. Neurovascular ischemic events were not predicted by SPECT variables. Conclusion: Myocardial perfusion scintigraphy predicts future CEs in patients with symptomatic ILA and may be helpful to guide therapeutic strategies in this subgroup of stroke patients.
Stroke after Burn
Authors: Cho Soo-Jin , Minn Yang-Ki , Kwon Ki-Han
Published: June 2007

Background: Stroke is regarded as a possible complication of burn. Some author reported that stroke developed in 22% of burned patients. However, the true incidence and the clinical characteristics of stroke occurring after burn injury are unknown. Methods: We reviewed the medical records of patients who had been admitted to the Burn Center at the Hangang Sacred Heart Hospital between January 1997 and May 2005. Patients with mild burns who did not require admission to the hospital were excluded from the study. Stroke patients were selected. Results: A total of 13,468 patients were admitted due to burn injury during the above-mentioned period. Nine (0.07%) patients (5 men, 4 women; mean age, 55 years) developed stroke while being under treatment for their burn injuries. The median duration between the burn injury and stroke onset was 33 days (range, 2–307). The mean surface area of the burn wound was 21% (range, 3–50). Ischemic infarction was observed in 4 patients, intracerebral hemorrhage in 3 others, and multiple hemorrhagic infarction and subdural hematoma in 1 patient each. Seven out of the 9 patients revealed the presence of septic conditions that occurred subsequent to the burn. Conclusion: Stroke is a rare complication of a burn injury in the clinical setting. It develops in moderate burns (10–50% of the total body surface area) after some time. Prevention of infection/sepsis is important to alleviate the occurrence of a stroke in these patients.
Everolimus Retards Cyst Growth and Preserves Kidney Function in a Rodent Model for Polycystic Kidney Disease
Authors: Wu Ming , Wahl Patricia R. , Le Hir Michel , Wäckerle-Men Ying , Wüthrich Rudolf P. , Serra Andreas L.
Published: June 2007

Background/Aims: Rapamycin inhibits cyst growth in polycystic kidney disease by targeting the mammalian target of rapamycin (mTOR). To determine if this is a class effect of the mTOR inhibitors, we examined the effect of everolimus, the analogue of rapamycin, on disease progression in the Han:SPRD rat model of polycystic kidney disease. Methods: Four-week-old male heterozygous cystic (Cy/+) and wild-type normal (+/+) Han:SPRD rats were administered everolimus or vehicle (3 mg/kg/day) by gavage for 5 weeks. Kidney function and whole-blood trough levels of everolimus were monitored. After treatment kidney weight and cyst volume density were assessed. Tubule epithelial cell proliferation was assessed by BrdU staining. Results: Everolimus trough levels between 5 and 7 µg/l were sufficient to significantly reduce kidney and cyst volume density by approximately 50 and 40%, respectively. The steady decrease of kidney function in Cy/+ rats was reduced by 30% compared with vehicle-treated Cy/+ rats. Everolimus treatment markedly reduced the number of 5-bromo-2-deoxyuridine-labeled nuclei in cyst epithelia. Body weight gain and kidney function were impaired in everolimus-treated wild-type rats. Conclusion: Moderate dosage of everolimus inhibits cystogenesis in Han:SPRD rats. The inhibitory effect of everolimus appears to represent a class effect of mTOR inhibitors.
Inhibitors of Factor VIIa/Tissue Factor
Authors: Shirk Rebecca A. , Vlasuk George P.
Published: June 2007

The formation of the proteolytic complex composed of the serine protease Factor VIIa and the cell-associated glycoprotein tissue factor (FVIIa/TF) initiates a cascade of amplified zymogen activation reactions leading to thrombus formation. The critical role of the coagulation cascade in pathological thrombosis has been the basis for significant efforts to design selective inhibitors of the protease components as new anticoagulant alternatives for the treatment of thrombotic diseases. However, for the new generation of anticoagulant drugs in development that primarily target protease complexes distal from FVIIa/TF, the differential between efficacy and safety as defined by bleeding is unresolved. Targeting the FVIIa/TF complex has several theoretical advantages that exploit the amplified nature of the coagulation cascade. However, progress on the development of clinical-stage FVIIa/TF-based anticoagulants has not been as successful to date. This review summarizes recent efforts in the discovery of synthetic inhibitors of FVIIa/TF.
Initial Experience of a Digital Training Resource for Modified Rankin Scale Assessment in Clinical Trials
Authors: Quinn Terence J. , Lees Kennedy R. , Hardemark Hans-Goran , Dawson Jesse , Walters Matthew R.
Published: June 2007

Background and Purpose—

The modified Rankin Scale (mRS) is the preferred measure of disability in cerebrovascular clinical trials, but its value is restricted by interobserver variability. Poor reliability reduces the statistical power of clinical trials and leads to underestimation of effect size. Strategies to improve mRS grading are required. Video training has previously improved application of the National Institutes of Health Stroke Scale in clinical research. We developed an mRS training resource in an attempt to minimize interobserver variability.

Methods—

We produced a complete training resource comprising an instructional DVD with accompanying written materials and assessment recordings of patient interviews. Formal assessment of training involved grading of real-life cases. Results of initial training and recertification were collected centrally and scored.

Results—

Data from 1564 assessments are presented. The majority of assessors were participating in 2 large prospective clinical stroke trials. Assessors represented a mixed group of disciplines and nationalities. After training, most trainees (90%) achieved certification in mRS assessment. The majority (85%) of investigators who did not reach an acceptable score on initial testing achieved certification after further exposure to the package.

Conclusions—

Mass training in mRS assessment for clinical trials is possible. We outline the development of a video-based training package, including technical issues, patient selection procedures, and methods of scoring and assessment. Certification results suggest that use of the resource can improve mRS grading. Acceptability of the training has been demonstrated by its successful use in 2 international acute stroke trials, SAINT 1 and CHANT.
Geographic Patterns in Overall and Specific Cardiovascular Disease Incidence in Apparently Healthy Men in the United States
Authors: Rich David Q. , Gaziano J. Michael , Kurth Tobias
Published: June 2007

Background and Purpose—

Residence in the Southeastern United States (US) has been linked to increased stroke incidence and mortality. However, data on regional variability in overall cardiovascular disease (CVD) and specific coronary heart disease incidence are sparse.

Methods—

We assessed the risk of major CVD (nonfatal stroke, nonfatal myocardial infarction, or death from CVD) and specific CVD associated with region of residence (Northeast, Southeast, Midwest, and West) in 17 927 apparently healthy male participants of the Physicians’ Health Study. Subjects were aged 40 to 84, most were white (93%), and had no previous CVD at baseline. We used residence in the Northeast as the reference group and proportional hazards models to adjust for potential confounding.

Results—

We found no difference in risk of major CVD between regions of residence. Further, we found no consistent association between myocardial infarction and CVD death and region of residence. In contrast, we found a significantly increased risk of total stroke (HR, 1.22; 95% CI, 1.02 to 1.47) associated with residence in the Southeast compared with the Northeast. This relative risk was further increased for ischemic stroke (HR, 1.30; 95% CI, 1.06 to 1.58). We saw no difference in risk of any outcome when categorizing state of residence into tertiles based on mean winter temperature, mean summer temperature, or into 2 groups based on latitude.

Conclusions—

In this homogenous and well-characterized cohort of US male physicians, we found greater incidence of ischemic stroke, but not other vascular event
s
among those living in the Southeastern US, compared with other regions.
Simulated Seasonal and Interannual Variability of the Mixed Layer Heat Budget in the Northern Indian Ocean*
Authors: Montégut Clémentde Boyer , Vialard Jérôme , Shenoi S. S. C. , Shankar D. , Durand Fabien , Ethé Christian , Madec Gurvan
Published: June 2007

A global ocean general circulation model (OGCM) is used to investigate the mixed layer heat budget of the northern Indian Ocean (NIO). The model is validated against observations and shows fairly good agreement with mixed layer depth data in the NIO. The NIO has been separated into three subbasins: the western Arabian Sea (AS), the eastern AS, and the Bay of Bengal (BoB). This study reveals strong differences between the western and eastern AS heat budget, while the latter basin has similarities with the BoB. Interesting new results on seasonal time scales are shown. The penetration of solar heat flux needs to be taken into account for two reasons. First, an average of 28 W m−2 is lost beneath the mixed layer over the year. Second, the penetration of solar heat flux tends to reduce the effect of solar heat flux on the SST seasonal cycle in the AS because the seasons of strongest flux are also seasons with a thin mixed layer. This enhances the control of SST seasonal variability by latent heat flux. The impact of salinity on SST variability is demonstrated. Salinity stratification plays a clear role in maintaining a high winter SST in the BoB and eastern AS while not in the western AS. The presence of freshwater near the surface allows heat storage below the surface layer that can later be recovered by entrainment warming during winter cooling (with a winter contribution of +2.1°C in the BoB). On an interannual time scale, the eastern AS and BoB are strongly controlled by the winds through the latent heat flux anomalies. In the western AS, vertical processes, as well as horizontal advection, contribute significantly to SST interannual variability, and the wind is not the only factor controlling the heat flux forcing.
The Years of El Niño, La Niña, and Interactions with the Tropical Indian Ocean
Authors: Meyers Gary , McIntosh Peter , Pigot Lidia , Pook Mike
Published: June 2007

The Indian Ocean zonal dipole is a mode of variability in sea surface temperature that seriously affects the climate of many nations around the Indian Ocean rim, as well as the global climate system. It has been the subject of increasing research, and sometimes of scientific debate concerning its existence/nonexistence and dependence/independence on/from the El Niño–Southern Oscillation, since it was first clearly identified in Nature in 1999. Much of the debate occurred because people did not agree on what years are the El Niño or La Niña years, not to mention the newly defined years of the positive or negative dipole. A method that identifies when the positive or negative extrema of the El Niño–Southern Oscillation and Indian Ocean dipole occur is proposed, and this method is used to classify each year from 1876 to 1999. The method is statistical in nature, but has a strong basis on the oceanic physical mechanisms that control the variability of the near-equatorial Indo-Pacific basin. Early in the study it was found that some years could not be clearly classified due to strong decadal variation; these years also must be recognized, along with the reason for their ambiguity. The sensitivity of the classification of years is tested by calculating composite maps of the Indo-Pacific sea surface temperature anomaly and the probability of below median Australian rainfall for different categories of the El Niño–Indian Ocean relationship.
Impacts of ENSO and Indian Ocean Dipole Events on the Southern Hemisphere Storm-Track Activity during Austral Winter
Authors: Ashok Karumuri , Nakamura Hisashi , Yamagata Toshio
Published: June 2007

Impacts of the ENSO and Indian Ocean dipole (IOD) phenomena on winter storm-track activity over the Southern Hemisphere are examined on the basis of the observed and reanalysis data for 1979–2003. The partial correlation technique is utilized to distinguish the impact of one phenomenon from that of the other. During an El Niño event, the subtropical jet stream tends to strengthen substantially, enhancing the jet bifurcation and thereby reducing storm-track activity over the midlatitude South Pacific and to the south of Australia. During a positive IOD event, the westerlies and storm-track activity also tend to weaken over southern Australia and portions of New Zealand. Thus both the positive IOD and, to a lesser extent, El Niño events act to reduce winter rainfall significantly over some portions of South Australia and New Zealand. Precipitation over the southeastern portion of the continent and over the northern portions of the two main islands of New Zealand is more sensitive to IOD. Significant reduction in precipitation associated with an El Niño event is seen over Tasmania. Over midlatitude South America, in contrast, the enhancement of the westerlies and storm-track activity tends to be more significant in a positive IOD event than in an El Niño event. It is demonstrated that despite the dominant influence of the Southern Hemispheric Annular Mode from a hemispheric viewpoint, the remote influence of ENSO and/or IOD on local storm-track activity can be detected in winter as a significant signal in particular midlatitude regions, including South Australia and New Zealand.