951 resultados para transient loads
Resumo:
BACKGROUND Elevated resting heart rate is known to be detrimental to morbidity and mortality in cardiovascular disease, though its effect in patients with ischemic stroke is unclear. We analyzed the effect of baseline resting heart rate on myocardial infarction (MI) in patients with a recent noncardioembolic cerebral ischemic event participating in PERFORM. METHODS We compared fatal or nonfatal MI using adjusted Cox proportional hazards models for PERFORM patients with baseline heart rate <70 bpm (n=8178) or ≥70 bpm (n=10,802). In addition, heart rate was analyzed as a continuous variable. Other cerebrovascular and cardiovascular outcomes were also explored. RESULTS Heart rate ≥70 bpm was associated with increased relative risk for fatal or nonfatal MI (HR 1.32, 95% CI 1.03-1.69, P=0.029). For every 5-bpm increase in heart rate, there was an increase in relative risk for fatal and nonfatal MI (11.3%, P=0.0002). Heart rate ≥70 bpm was also associated with increased relative risk for a composite of fatal or nonfatal ischemic stroke, fatal or nonfatal MI, or other vascular death (excluding hemorrhagic death) (P<0001); vascular death (P<0001); all-cause mortality (P<0001); and fatal or nonfatal stroke (P=0.04). For every 5-bpm increase in heart rate, there were increases in relative risk for fatal or nonfatal ischemic stroke, fatal or nonfatal MI, or other vascular death (4.7%, P<0.0001), vascular death (11.0%, P<0.0001), all-cause mortality (8.0%, P<0.0001), and fatal and nonfatal stroke (2.4%, P=0.057). CONCLUSION Elevated heart rate ≥70 bpm places patients with a noncardioembolic cerebral ischemic event at increased risk for MI.
Resumo:
Syncope describes a sudden and brief transient loss of consciousness (TLOC) with postural failure due to cerebral global hypoperfusion. The term TLOC is used when the cause is either unrelated to cerebral hypoperfusion or is unknown. The most common causes of syncopal TLOC include: (1) cardiogenic syncope (cardiac arrhythmias, structural cardiac diseases, others); (2) orthostatic hypotension (due to drugs, hypovolemia, primary or secondary autonomic failure, others); (3) neurally mediated syncope (cardioinhibitory, vasodepressor, and mixed forms). Rarely neurologic disorders (such as epilepsy, transient ischemic attacks, and the subclavian steal syndrome) can lead to cerebal hypoperfusion and syncope. Nonsyncopal TLOC may be due to neurologic (epilepsy, sleep attacks, and other states with fluctuating vigilance), medical (hypoglycemia, drugs), psychiatric, or post-traumatic disorders. Basic diagnostic workup of TLOC includes a thorough history and physical examination, and a 12-lead electrocardiogram (ECG). Blood testing, electroencephalogram (EEG), magnetic resonance imaging (MRI) of the brain, echocardiography, head-up tilt test, carotid sinus massage, Holter monitoring, and loop recorders should be obtained only in specific contexts. Management strategies involve pharmacologic and nonpharmacologic interventions, and cardiac pacing.
Resumo:
We describe the case of a 35-year-old female patient who suffered from fulminant tick-borne encephalitis and subsequently died. Remarkable about this case was that the woman was not living in an endemic area and that the disease occurred outside the usual season. Furthermore, this indicates that an increase in transmission of tick-borne encephalitis can be expected outside the classical endemic areas in higher altitudes, possibly as a consequence of climate changes.
Resumo:
User comfort during simulated driving is of key importance, since reduced comfort can confound the experiment and increase dropout rates. A common comfort-affecting factor is simulator-related transient adverse health effect (SHE). In this study, we propose and evaluate methods to adapt a virtual driving scene to reduce SHEs. In contrast to the manufacturer-provided high-sensory conflict scene (high-SCS), we developed a low-sensory conflict scene (low-SCS). Twenty young, healthy participants drove in both the high-SCS and the low-SCS scene for 10 min on two different days (same time of day, randomized order). Before and after driving, participants rated SHEs by completing the Simulator Sickness Questionnaire (SSQ). During driving, several physiological parameters were recorded. After driving in the high-SCS, the SSQ score increased in average by 129.4 (122.9 %, p = 0.002) compared to an increase of 5.0 (3.4 %, p = 0.878) after driving in the low-SCS. In the low-SCS, skin conductance decreased by 13.8 % (p < 0.01) and saccade amplitudes increased by 16.1 % (p < 0.01). Results show that the investigated methods reduce SHEs in a younger population, and the low-SCS is well accepted by the users. We expect that these measures will improve user comfort.
Resumo:
In several studies of antiretroviral treatment (ART) programs for persons with human immunodeficiency virus infection, investigators have reported that there has been a higher rate of loss to follow-up (LTFU) among patients initiating ART in recent years than among patients who initiated ART during earlier time periods. This finding is frequently interpreted as reflecting deterioration of patient retention in the face of increasing patient loads. However, in this paper we demonstrate by simulation that transient gaps in follow-up could lead to bias when standard survival analysis techniques are applied. We created a simulated cohort of patients with different dates of ART initiation. Rates of ART interruption, ART resumption, and mortality were assumed to remain constant over time, but when we applied a standard definition of LTFU, the simulated probability of being classified LTFU at a particular ART duration was substantially higher in recently enrolled cohorts. This suggests that much of the apparent trend towards increased LTFU may be attributed to bias caused by transient interruptions in care. Alternative statistical techniques need to be used when analyzing predictors of LTFU-for example, using "prospective" definitions of LTFU in place of "retrospective" definitions. Similar considerations may apply when analyzing predictors of LTFU from treatment programs for other chronic diseases.
Resumo:
Acquired Fanconi syndrome is characterized by inappropriate urinary loss of amino acids, bicarbonate, electrolytes, and water. It has recently been described in dogs fed chicken jerky treats from China, a new differential diagnosis to the classical inciting infectious diseases (e.g. leptospirosis, pyelonephritis) and toxins. A dog fed exclusively chicken jerky treats purchased in Switzerland was presented to our clinic with severe polyuria, polydipsia and profound electrolyte and acid base disturbances. Other inciting causes of Fanconi syndrome were ruled out. The requirement of a very intensive supportive treatment in this dog stands in contrast to treatment of chronic forms of Fanconi syndrome as described in the Basenji. This intensive therapy and the associated monitoring can be a real challenge and a limiting factor for the prognosis of acquired Fanconi syndrome. Veterinarians should be aware of the risk of excessive feeding of chicken jerky treats.
Resumo:
BACKGROUND AND PURPOSE To assess the association of lesion location and risk of aspiration and to establish predictors of transient versus extended risk of aspiration after supratentorial ischemic stroke. METHODS Atlas-based localization analysis was performed in consecutive patients with MRI-proven first-time acute supratentorial ischemic stroke. Standardized swallowing assessment was carried out within 8±18 hours and 7.8±1.2 days after admission. RESULTS In a prospective, longitudinal analysis, 34 of 94 patients (36%) were classified as having acute risk of aspiration, which was extended (≥7 days) or transient (<7 days) in 17 cases. There were no between-group differences in age, sex, cause of stroke, risk factors, prestroke disability, lesion side, or the degree of age-related white-matter changes. Correcting for stroke volume and National Institutes of Health Stroke Scale with a multiple logistic regression model, significant adjusted odds ratios in favor of acute risk of aspiration were demonstrated for the internal capsule (adjusted odds ratio, 6.2; P<0.002) and the insular cortex (adjusted odds ratio, 4.8; P<0.003). In a multivariate model of extended versus transient risk of aspiration, combined lesions of the frontal operculum and insular cortex was the only significant independent predictor of poor recovery (adjusted odds ratio, 33.8; P<0.008). CONCLUSIONS Lesions of the insular cortex and the internal capsule are significantly associated with acute risk of aspiration after stroke. Combined ischemic infarctions of the frontal operculum and the insular cortex are likely to cause extended risk of aspiration in stroke patients, whereas risk of aspiration tends to be transient in subcortical stroke.
Resumo:
BACKGROUND AND PURPOSE Copeptin has been associated with recurrent cerebrovascular events after transient ischemic attack (TIA). In an independent cohort, we evaluated copeptin for the prediction of recurrent cerebrovascular events within 3 months after TIA and assessed the incremental value of copeptin compared with the ABCD2 (age, blood, clinical features of TIA, duration of symptoms, presence of diabetes mellitus) and ABCD3-I (ABCD2, dual TIA [the presence of ≥2 TIA symptoms within 7 days], imaging [the presence of abnormal findings on neuroimaging]) scores. METHODS This prospective, multicenter cohort study was conducted at 3 tertiary Stroke Centers in Switzerland and Germany. RESULTS From March 2009 through April 2011, we included 302 patients with TIA admitted within 24 hours from symptom onset. Of 28 patients with a recurrent cerebrovascular event within 3 months (stroke or TIA), 11 patients had a stroke. Although the association of copeptin with recurrent cerebrovascular events was not significant, the association with stroke alone as end point was significant. After adjusting for the ABCD2 score, a 10-fold increase in copeptin levels was associated with an odds ratio for stroke of 3.39 (95% confidence interval, 1.28-8.96; P=0.01). After addition of copeptin to the ABCD2 score, the area under the curve of the ABCD2 score improved from 0.60 (95% confidence interval, 0.46-0.74) to 0.74 (95% confidence interval, 0.60-0.88, P=0.02). In patients with MRI (n=223), the area under the curve of the ABCD3-I score increased in similar magnitude, although not significantly. Based on copeptin, 31.2% of patients were correctly reclassified across the risk categories of the ABCD2 score (net reclassification improvement; P=0.17). CONCLUSIONS Copeptin improved the prognostic value of the ABCD2 score for the prediction of stroke but not TIA, and it may help clinicians in refining risk stratification for patients with TIA. CLINICAL TRIAL REGISTRATION URL http://www.clinicaltrials.gov. Unique identifier: NCT00878813.
Resumo:
BACKGROUND AND PURPOSE Visit-to-visit variability in systolic blood pressure (SBP) is associated with an increased risk of stroke and was reduced in randomized trials by calcium channel blockers and diuretics but not by renin-angiotensin system inhibitors. However, time of day effects could not be determined. Day-to-day variability on home BP readings predicts stroke risk and potentially offers a practical method of monitoring response to variability-directed treatment. METHODS SBP mean, maximum, and variability (coefficient of variation=SD/mean) were determined in 500 consecutive transient ischemic attack or minor stroke patients on 1-month home BP monitoring (3 BPs, 3× daily). Hypertension was treated to a standard protocol. Differences in SBP variability from 3 to 10 days before to 8 to 15 days after starting or increasing calcium channel blockers/diuretics versus renin-angiotensin system inhibitors versus both were compared by general linear models, adjusted for risk factors and baseline BP. RESULTS Among 288 eligible interventions, variability in SBP was reduced after increased treatment with calcium channel blockers/diuretics versus both versus renin-angiotensin system inhibitors (-4.0 versus 6.9 versus 7.8%; P=0.015), primarily because of effects on maximum SBP (-4.6 versus -1.0 versus -1.0%; P=0.001), with no differences in effect on mean SBP. Class differences were greatest for early-morning SBP variability (3.6 versus 17.0 versus 38.3; P=0.002) and maximum (-4.8 versus -2.0 versus -0.7; P=0.001), with no effect on midmorning (P=0.29), evening (P=0.65), or diurnal variability (P=0.92). CONCLUSIONS After transient ischemic attack or minor stroke, calcium channel blockers and diuretics reduced variability and maximum home SBP, primarily because of effects on morning readings. Home BP readings enable monitoring of response to SBP variability-directed treatment in patients with recent cerebrovascular events.
Resumo:
Transient exposure of brown trout embryos from fertilization until hatch (70 days) to 17β-estradiol (E2) was investigated. Embryos were exposed to 3.8 and 38.0 ng/L E2 for 2h, respectively, under four scenarios: (A) exposure once at the day of fertilization (0 days post-fertilization, dpf), (B) once at eyeing stage (38 dpf), (C) weekly exposure until hatch or (D) bi-weekly exposure until hatch. Endpoints to assess estrogen impact on embryo development were fertilization success, chronological sequence of developmental events, hatching process, larval malformations, heart rate, body length and mortality. Concentration-dependent acceleration of development until median hatch was observed in all exposure scenarios with the strongest effect observed for embryos exposed once at 0 dpf. In addition, the hatching period was significantly prolonged by 4-5 days in groups receiving single estrogen exposures (scenarios A and B). Heart rate on hatching day was significantly depressed with increasing E2 concentrations, with the strongest effect observed for embryos exposed at eyeing stage. Estrogenic exposure at 0 dpf significantly reduced body length at hatch, not depending on whether this was a single exposure or the first of a series (scenarios A and D). The key finding is that even a single, transient E2 exposure during embryogenesis had significant effects on brown trout development. Median hatch, hatching period, heart rate and body length at hatch were found to be highly sensitive biomarkers responsive to estrogenic exposure during embryogenesis. Treatment effects were observable only at the post-hatch stage.
Resumo:
Although beryllium-10 (10Be) concentrations in stream sediments provide useful synoptic views of catchment-wide erosion rates, little is known on the relative contributions of different sediment supply mechanisms to the acquisition of their initial signature in the headwaters. Here we address this issue by conducting a 10Be-budget of detrital materials that characterize the morphogenetic domains representative of high-altitude environments of the European Alps. We focus on the Etages catchment, located in the Ecrins-Pelvoux massif (southeast France), and illustrate how in situ 10Be concentrations can be used for tracing the origin of the sand fraction from the bedload in the trunk stream. The landscape of the Etages catchment is characterized by a geomorphic transient state, high topographic gradients, and a large variety of modern geomorphic domains ranging from glacial environments to scarcely vegetated alluvial plains. Beryllium-10 concentrations measured in the Etages catchment vary from similar to 1 x 104 to 4.5 x 105 atoms per gram quartz, while displaying consistent 10Be signatures within each representative morphogenetic unit. We show that the basic requirements for inferring catchment-wide denudation from 10Be concentration measurements are not satisfied in this small, dynamic catchment. However, the distinct 10Be signature observed for the geomorphic domains can be used as a tracer. We suggest that a terrestrial cosmogenic nuclide (TCN) budget approach provides a valuable tool for the tracing of material origin in basins where the let nature do the averaging' principles may be violated.
Resumo:
In prospective memory tasks different kinds of load can occur. Adding a prospective memory task can impose a load on ongoing task performance. Adding ongoing task load (OTL) can affect prospective memory performance. The existence of multiple target events increases prospective load (PL) and adding complexity to the to-be-remembered action increases retrospective load (RL). In two experiments, we systematically examined the effects of these different types of load on prospective memory performance. Results showed an effect of PL on costs in the ongoing task for categorical targets (Experiment 2), but not for specific targets (Experiment 1). RL and OTL both affected remembering the retrospective component of the prospective memory task. We suggest that PL can enhance costs in the ongoing task due to additional monitoring requirements. RL and OTL seem to impact the division of resources between the ongoing task and retrieval of the retrospective component, which may affect disengagement from the ongoing task. In general, the results demonstrate that the different types of load affect prospective memory differentially.
Resumo:
Information on the relationship between cumulative fossil CO2 emissions and multiple climate targets is essential to design emission mitigation and climate adaptation strategies. In this study, the transient response of a climate or environmental variable per trillion tonnes of CO2 emissions, termed TRE, is quantified for a set of impact-relevant climate variables and from a large set of multi-forcing scenarios extended to year 2300 towards stabilization. An ∼ 1000-member ensemble of the Bern3D-LPJ carbon–climate model is applied and model outcomes are constrained by 26 physical and biogeochemical observational data sets in a Bayesian, Monte Carlo-type framework. Uncertainties in TRE estimates include both scenario uncertainty and model response uncertainty. Cumulative fossil emissions of 1000 Gt C result in a global mean surface air temperature change of 1.9 °C (68 % confidence interval (c.i.): 1.3 to 2.7 °C), a decrease in surface ocean pH of 0.19 (0.18 to 0.22), and a steric sea level rise of 20 cm (13 to 27 cm until 2300). Linearity between cumulative emissions and transient response is high for pH and reasonably high for surface air and sea surface temperatures, but less pronounced for changes in Atlantic meridional overturning, Southern Ocean and tropical surface water saturation with respect to biogenic structures of calcium carbonate, and carbon stocks in soils. The constrained model ensemble is also applied to determine the response to a pulse-like emission and in idealized CO2-only simulations. The transient climate response is constrained, primarily by long-term ocean heat observations, to 1.7 °C (68 % c.i.: 1.3 to 2.2 °C) and the equilibrium climate sensitivity to 2.9 °C (2.0 to 4.2 °C). This is consistent with results by CMIP5 models but inconsistent with recent studies that relied on short-term air temperature data affected by natural climate variability.
Resumo:
BACKGROUND Temporary increases in plasma HIV RNA ('blips') are common in HIV patients on combination antiretroviral therapy (cART). Blips above 500 copies/mL have been associated with subsequent viral rebound. It is not clear if this relationship still holds when measurements are made using newer more sensitive assays. METHODS We selected antiretroviral-naive patients that then recorded one or more episodes of viral suppression on cART with HIV RNA measurements made using more sensitive assays (lower limit of detection below 50 copies/ml). We estimated the association in these episodes between blip magnitude and the time to viral rebound. RESULTS Four thousand ninety-four patients recorded a first episode of viral suppression on cART using more sensitive assays; 1672 patients recorded at least one subsequent suppression episode. Most suppression episodes (87 %) were recorded with TaqMan version 1 or 2 assays. Of the 2035 blips recorded, 84 %, 12 % and 4 % were of low (50-199 copies/mL), medium (200-499 copies/mL) and high (500-999 copies/mL) magnitude respectively. The risk of viral rebound increased as blip magnitude increased with hazard ratios of 1.20 (95 % CI 0.89-1.61), 1.42 (95 % CI 0.96-2.19) and 1.93 (95 % CI 1.24-3.01) for low, medium and high magnitude blips respectively; an increase of hazard ratio 1.09 (95 % CI 1.03 to 1.15) per 100 copies/mL of HIV RNA. CONCLUSIONS With the more sensitive assays now commonly used for monitoring patients, blips above 200 copies/mL are increasingly likely to lead to viral rebound and should prompt a discussion about adherence.
Resumo:
Femtosecond Raman rotational coherence spectroscopy (RCS) detected by degenerate four-wave mixing is a background-free method that allows to determine accurate gas-phase rotational constants of non-polar molecules. Raman RCS has so far mostly been applied to the regular coherence patterns of symmetric-top molecules, while its application to nonpolar asymmetric tops has been hampered by the large number of RCS transient types, the resulting variability of the RCS patterns, and the 10³–10⁴ times larger computational effort to simulate and fit rotational Raman RCS transients. We present the rotational Raman RCS spectra of the nonpolar asymmetric top 1,4-difluorobenzene (para-difluorobenzene, p-DFB) measured in a pulsed Ar supersonic jet and in a gas cell over delay times up to ~2.5 ns. p-DFB exhibits rotational Raman transitions with ΔJ = 0, 1, 2 and ΔK = 0, 2, leading to the observation of J −, K −, A −, and C–type transients, as well as a novel transient (S–type) that has not been characterized so far. The jet and gas cell RCS measurements were fully analyzed and yield the ground-state (v = 0) rotational constants Aₒ = 5637.68(20) MHz, Bₒ = 1428.23(37) MHz, and Cₒ = 1138.90(48) MHz (1σ uncertainties). Combining the Aₒ, Bₒ, and Cₒ constants with coupled-cluster with single-, double- and perturbatively corrected triple-excitation calculations using large basis sets allows to determine the semi-experimental equilibrium bond lengths rₑ(C₁–C₂) = 1.3849(4) Å, rₑ(C₂–C³) = 1.3917(4) Å, rₑ(C–F) = 1.3422(3) Å, and rₑ(C₂–H₂) = 1.0791(5) Å.