997 resultados para Geometric characteristics


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Quantitative information from magnetic resonance imaging (MRI) may substantiate clinical findings and provide additional insight into the mechanism of clinical interventions in therapeutic stroke trials. The PERFORM study is exploring the efficacy of terutroban versus aspirin for secondary prevention in patients with a history of ischemic stroke. We report on the design of an exploratory longitudinal MRI follow-up study that was performed in a subgroup of the PERFORM trial. An international multi-centre longitudinal follow-up MRI study was designed for different MR systems employing safety and efficacy readouts: new T2 lesions, new DWI lesions, whole brain volume change, hippocampal volume change, changes in tissue microstructure as depicted by mean diffusivity and fractional anisotropy, vessel patency on MR angiography, and the presence of and development of new microbleeds. A total of 1,056 patients (men and women ≥ 55 years) were included. The data analysis included 3D reformation, image registration of different contrasts, tissue segmentation, and automated lesion detection. This large international multi-centre study demonstrates how new MRI readouts can be used to provide key information on the evolution of cerebral tissue lesions and within the macrovasculature after atherothrombotic stroke in a large sample of patients.

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BACKGROUND: Patients with venous thromboembolism (VTE) treated with anticoagulants are at risk of death from pulmonary embolism (PE) and/or bleeding. However, whether patients who develop VTE in hospital have a higher complication rate than those who develop VTE in an outpatient setting is unclear. PATIENTS AND METHODS: RIETE is an ongoing, prospective registry of consecutive patients with acute, objectively confirmed, symptomatic VTE. We compared the 3-month incidence of fatal PE and fatal bleeding in patients in whom the VTE had developed while in hospital for another medical condition (inpatients) with those who presented to the emergency ward because of VTE (outpatients). RESULTS: Up to April 2008, 22,133 patients with acute VTE were enrolled: 10,461 (47%) presented with PE, 11,672 with deep vein thrombosis. Overall, 6445 (29%) were inpatients. During the study period, those who developed VTE as inpatients had a significantly higher incidence of fatal PE (2.1% vs. 1.5%; odds ratio: 1.4; 95% CI: 1.1-1.7), overall death (7.0% vs. 5.4%; odds ratio: 1.3; 95% CI: 1.2-1.5), and major bleeding (2.9% vs. 2.1%; odds ratio: 1.4; 95% CI: 1.1-1.6) than outpatients. The incidence of fatal bleeding was not significantly increased (0.7% vs. 0.5%; odds ratio: 1.2; 95% CI: 0.9-1.8). In multivariable analysis, inpatient status was significantly associated with a higher risk for fatal PE (odds ratio: 1.3; 95% CI: 1.1-1.7). CONCLUSIONS: VTE occurring in hospitalized patients carries a significantly higher risk for death of PE than in outpatients, underscoring the importance of VTE prevention strategies in the hospital setting.

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ABSTRACT Humic acids (HA) are a component of humic substances (HS), which are found in nearly all soils, sediments, and waters. They play a key role in many, if not most, chemical and physical properties in their environment. Despite the importance of HA, their high complexity makes them a poorly understood system. Therefore, understanding the physicochemical properties and interactions of HA is crucial for determining their fundamental role and obtaining structural details. Cationic surfactants are known to interact electrostatically and hydrophobically with HA. Because they are a very well-known and characterized system, they offer a good choice as molecular probes for studying HA. The objective of this study was to evaluate the interaction between cationic surfactants and HA through isothermal titration calorimetry in a thermodynamic manner, aiming to obtain information about the basic structure of HA, the nature of this interaction, and if HA from different origins show different basic structures. Contrary to what the supramolecular model asserts, HA structure is not loosely held, though it may separate depending on the conditions the HA are subjected to in their milieu. It did not show any division or conformational change when interacting with surfactants. The basic structure of the HA remains virtually the same regardless of the different sources and compositions of these HA.

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Safety i s a very important aspect o f the highway program. The Iowa DOT initiated an inventory o f the friction values of all paved primary roadways i n 1969. This inventory, with an ASTM E-274 test unit, has continued to the present time. The t e s t i n g frequency varies based upon traffic volume and the previous friction value. Historically , the state o f Iowa constructed a substantial amount o f pcc pavement during the 1928-30 period t o "get Iowa out o f the mud". Some of that pavement has never been resurfaced and has been subjected to more than 50 years o f wear. The textured surface has been worn away and has subsequently polished. Even though some pavements from 15 t o 50 years old continue t o function structurally , because of the loss of friction , they do not provide the desired level o f safety to the driver. As a temporary measure, "Sl ippery -When -Wet " signs have been posted on many older pcc roads due to friction numbers below t h e desirable level. These signs warn the motorist of the current conditions. An economical method of restoring the high quality frictional properties i s needed.

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An experimental modification of the transverse groove surface texture of a section of an urban interstate highway was performed by the Iowa Department of Transportation. Transverse groove texturing i s a design feature required by the Federal Highway Administration t o reduce skidding under wet pavement conditions. Adjacent residents claimed the texturing was the cause of especially annoying tonal characteristics within the traffic noise. A research proposal to modify the existing texture pattern by surface grinding and to study the noise and friction effects was approved for funding by the Iowa Highway Research Board. Results i n the form of a comparison between traffic noise before modification and traffic noise immediately after and 15 months after modification indicate that the change in surface texture has lowered overall traffic noise levels by reducing a high frequency component of the traffic noise spectrum. Fraffic testing data show reduced capacity of the roadway to inhibit wet pavement skidding as a result of the surface modification.

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OBJECTIVE: The pathophysiologic concept of Ménière's disease assumes that endolymphatic hydrops is the cause of the symptoms via increased pressure in the endolymphatic space and/or ionic disorder due to ruptured membrane. The goal of this study was to assess whether the vestibulo-ocular reflex (VOR) properties in patients with Ménière's disease were consistent with the classical theory. MATERIAL AND METHODS: We studied 34 patients (19 women, 15 men) presenting with unilateral Ménière's disease divided into 2 groups according to the duration of the disease: 18 were in the early stage (< 12 mo), and 16 were in the late stage (> or = 12 mo). Nineteen patients were examined during an attack. Eight of them and the 15 other patients were tested during the interval between attacks. Their characteristics were compared with those of a group of 22 normal subjects. The VOR function was evaluated via standard caloric and impulse rotatory tests (velocity step). A mathematic model of vestibular function was used to characterize the VOR response to rotational stimulation. Dynamic VOR parameters (sensitivity coefficient, time constant, gain, and asymmetries between the 2 directions of rotation) were statistically compared between the 2 groups of patients during and between attacks and between the patients and controls. RESULTS: All dynamic VOR parameters showed no statistically significant difference both with normal controls and among the patients during and between attacks (p > 0.05) except for gain asymmetry (p < or = 0.008). During attacks, patients with early Ménière's disease displayed a higher gain in rotation toward the affected ear, the opposite being observed in patients with late disease. Caloric test revealed a moderate canal paresis on the affected side during the crisis and a slight asymmetry between attacks. CONCLUSION: During attacks in patients with early Ménière's disease, the VOR gain toward the affected side is higher than that toward the intact side, supporting the fact that that the sensitivity of the cupuloendolymphatic system on the affected ear is increased. This observation is in agreement with a mechanical pressure effect of hydrops on the vestibular organs.

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We give a geometric description of the interpolating varieties for the algebra of Fourier transforms of distributions (or Beurling ultradistributions) with compact support on the real line.

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BACKGROUND: Human speech is greatly influenced by the speakers' affective state, such as sadness, happiness, grief, guilt, fear, anger, aggression, faintheartedness, shame, sexual arousal, love, amongst others. Attentive listeners discover a lot about the affective state of their dialog partners with no great effort, and without having to talk about it explicitly during a conversation or on the phone. On the other hand, speech dysfunctions, such as slow, delayed or monotonous speech, are prominent features of affective disorders. METHODS: This project was comprised of four studies with healthy volunteers from Bristol (English: n = 117), Lausanne (French: n = 128), Zurich (German: n = 208), and Valencia (Spanish: n = 124). All samples were stratified according to gender, age, and education. The specific study design with different types of spoken text along with repeated assessments at 14-day intervals allowed us to estimate the 'natural' variation of speech parameters over time, and to analyze the sensitivity of speech parameters with respect to form and content of spoken text. Additionally, our project included a longitudinal self-assessment study with university students from Zurich (n = 18) and unemployed adults from Valencia (n = 18) in order to test the feasibility of the speech analysis method in home environments. RESULTS: The normative data showed that speaking behavior and voice sound characteristics can be quantified in a reproducible and language-independent way. The high resolution of the method was verified by a computerized assignment of speech parameter patterns to languages at a success rate of 90%, while the correct assignment to texts was 70%. In the longitudinal self-assessment study we calculated individual 'baselines' for each test person along with deviations thereof. The significance of such deviations was assessed through the normative reference data. CONCLUSIONS: Our data provided gender-, age-, and language-specific thresholds that allow one to reliably distinguish between 'natural fluctuations' and 'significant changes'. The longitudinal self-assessment study with repeated assessments at 1-day intervals over 14 days demonstrated the feasibility and efficiency of the speech analysis method in home environments, thus clearing the way to a broader range of applications in psychiatry. © 2014 S. Karger AG, Basel.

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Using the Xenopus oocyte expression system, we have previously identified an approximately 4-kb fraction of mRNA from rat liver that expresses sulfobromophthalein-glutathione (BSP-GSH)-insensitive reduced glutathione (GSH) transport (Fernandez-Checa, J., J. R. Yi, C. Garcia-Ruiz, Z. Knezic, S. Tahara, and N. Kaplowitz. 1993. J. Biol. Chem. 268:2324-2328). Starting with a cDNA library constructed from this fraction, we have now isolated a single clone that expresses GSH transporter activity. The cDNA for the rat canalicular GSH transporter (RcGshT) is 4.05 kb with an open reading frame of 2,505 nucleotides encoding for a polypeptide of 835 amino acids (95,785 daltons). No identifiable homologies were found in searching various databases. An approximately 96-kD protein is generated in in vitro translation of cRNA for RcGshT. Northern blot analysis reveals a single 4-kb transcript in liver, kidney, intestine, lung, and brain. The abundance of mRNA for RcGshT in rat liver increased 3, 6, and 12 h after a single dose of phenobarbital. Insensitivity to BSP-GSH and induction by phenobarbital, unique characteristics of canalicular GSH secretion, suggest that RcGshT encodes for the canalicular GSH transporter.

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BACKGROUND: Raltegravir (RAL) achieved remarkable virologic suppression rates in randomized-clinical trials, but today efficacy data and factors for treatment failures in a routine clinical care setting are limited. METHODS: First, factors associated with a switch to RAL were identified with a logistic regression including patients from the Swiss HIV Cohort Study with a history of 3 class failure (n = 423). Second, predictors for virologic outcome were identified in an intent-to-treat analysis including all patients who received RAL. Last observation carried forward imputation was used to determine week 24 response rate (HIV-1 RNA >or= 50 copies/mL). RESULTS: The predominant factor associated with a switch to RAL in patients with suppressed baseline RNA was a regimen containing enfuvirtide [odds ratio 41.9 (95% confidence interval: 11.6-151.6)]. Efficacy analysis showed an overall response rate of 80.9% (152/188), whereas 71.8% (84/117) and 95.8% (68/71) showed viral suppression when stratified for detectable and undetectable RNA at baseline, respectively. Overall CD4 cell counts increased significantly by 42 cells/microL (P < 0.001). Characteristics of failures were a genotypic sensitivity score of the background regimen <or=1, very low RAL plasma concentrations, poor adherence, and high viral load at baseline. CONCLUSIONS: Virologic suppression rates in our routine clinical care setting were promising and comparable with data from previously published randomized-controlled trials.