This paper presents a study of the energetics of the dayside ionosphere of Mars using models and data from several instruments on board the Mars Atmosphere and Volatile EvolutioN spacecraft. In ...particular, calculated photoelectron fluxes are compared with suprathermal electron fluxes measured by the Solar Wind Electron Analyzer, and calculated electron temperatures are compared with temperatures measured by the Langmuir Probe and Waves experiment. The major heat source for the thermal electrons is Coulomb heating from the suprathermal electron population, and cooling due to collisional rotational and vibrational CO2 dominates the energy loss. The models used in this study were largely able to reproduce the observed high topside ionosphere electron temperatures (e.g., 3000 K at 300 km altitude) without using a topside heat flux when magnetic field topologies consistent with the measured magnetic field were adopted. Magnetic topology affects both suprathermal electron transport and thermal electron heat conduction. The effects of using two different solar irradiance models were also investigated. In particular, photoelectron fluxes and electron temperatures found using the Heliospheric Environment Solar Spectrum Radiation irradiance were higher than those with the Flare Irradiance Spectrum Model-Mars. The electron temperature is shown to affect the O2(+) dissociative recombination rate coefficient, which in turn affects photochemical escape of oxygen from Mars.
This study tested the hypothesis that stroke patients without a cardiac source of embolism suspected by clinical examination can be risk stratified by transesophageal echocardiography. Forty ischemic ...stroke patients without atrial fibrillation, prosthetic valves, ejection fraction <20%, or recent myocardial infarction underwent multiplane transesophageal echocardiography: 24 (designated high risk) had ≥1 of the following: left heart thrombus, vegetation, mass or spontaneous echo contrast, mobile ascending aortic or arch debris, patent foramen ovale, atrial septal defect or aneurysm, mitral annular calcification, mitral valve thickening, prolapse or mitral valve strands. End points were death, recurrent stroke, transient ischemic attack, myocardial infarction or peripheral embolism. Thirty-eight patients (95%) (23 high, 15 low risk) were followed for 14 ± 8 months: 9 (24%) died of vascular causes including 4 who had a cardiac cause of death and 5 who had fatal strokes. Eight had recurrent strokes (4 nonfatal) and 1 nonfatal myocardial infarction occurred. Cardiovascular survival was predicted by transesophageal echocardiography: survival rates were 92% (low risk) and 63% (high risk) at 24 months (p = 0.036). Left atrial enlargement was independently associated with death from stroke (fatal stroke occurred in 25% of those with atrial enlargement compared to 8% of those with normal atrial dimension, p ≤0.03), as was left atrial spontaneous echo contrast (50% died vs 9% without contrast, p ≤0.03). Left ventricular hypertrophy and aortic atherosclerosis were both associated with the risk of recurrent stroke (30% of patients with ventricular hypertrophy had recurrent stroke compared to 10% with normal wall thickness (p ≤0.05); 30% with aortic atherosclerosis had a recurrent stroke compared to none with a normal aorta (p ≤0.05). Thus, transesophageal echocardiography clearly identifies patients at a high risk for cardiovascular mortality and morbidity after stroke despite an unsuspected source of embolism by clinical examination.
This study sought to compare a continuous infusion diuretic strategy versus an intermittent bolus diuretic strategy, with the addition of low-dose dopamine (3 μg/kg/min) in the treatment of ...hospitalized patients with heart failure with preserved ejection fraction (HFpEF).
HFpEF patients are susceptible to development of worsening renal function (WRF) when hospitalized with acute heart failure; however, inpatient treatment strategies to achieve safe and effective diuresis in HFpEF patients have not been studied to date.
In a prospective, randomized, clinical trial, 90 HFpEF patients hospitalized with acute heart failure were randomized within 24 h of admission to 1 of 4 treatments: 1) intravenous bolus furosemide administered every 12 h; 2) continuous infusion furosemide; 3) intermittent bolus furosemide with low-dose dopamine; and 4) continuous infusion furosemide with low-dose dopamine. The primary endpoint was percent change in creatinine from baseline to 72 h. Linear and logistic regression analyses with tests for interactions between diuretic and dopamine strategies were performed.
Compared to intermittent bolus strategy, the continuous infusion strategy was associated with higher percent increase in creatinine (continuous infusion: 16.01%; 95% confidence interval CI: 8.58% to 23.45% vs. intermittent bolus: 4.62%; 95% CI: −1.15% to 10.39%; p = 0.02). Low-dose dopamine had no significant effect on percent change in creatinine (low-dose dopamine: 12.79%; 95% CI: 5.66% to 19.92%, vs. no-dopamine: 8.03%; 95% CI: 1.44% to 14.62%; p = 0.33). Continuous infusion was also associated with greater risk of WRF than intermittent bolus (odds ratio OR: 4.32; 95% CI: 1.26 to 14.74; p = 0.02); no differences in WRF risk were seen with low-dose dopamine. No significant interaction was seen between diuretic strategy and low-dose dopamine (p > 0.10).
In HFpEF patients hospitalized with acute heart failure, low-dose dopamine had no significant impact on renal function, and a continuous infusion diuretic strategy was associated with renal impairment. (Diuretics and Dopamine in Heart Failure With Preserved Ejection Fraction ROPA-DOP; NCT01901809)
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Many hospitals are investing in computer-based provider order-entry (POE) systems, and providers' evaluations have proved important for the success of the systems. The authors assessed how physicians ...and nurses viewed the effects of one modified commercial POE system on time spent patients, resource utilization, errors with orders, and overall quality of care.
Survey.
Opinions of 271 POE users on medicine wards of an urban teaching hospital: 96 medical house officers, 49 attending physicians, 19 clinical fellows with heavy inpatient loads, and 107 nurses.
Responses were received from 85 percent of the sample. Most physicians and nurses agreed that orders were executed faster under POE. About 30 percent of house officers and attendings or fellows, compared with 56 percent of nurses, reported improvement in overall quality of care with POE. Forty-four percent of house officers and 34 percent of attendings/fellows reported that their time with patients decreased, whereas 56 percent of nurses indicated that their time with patients increased (P < 0.001). Sixty percent of house officers and 41 percent of attendings/fellows indicated that order errors increased, whereas 69 percent of nurses indicated a decrease or no change in errors. Although most nurses reported no change in the frequency of ordering tests and medications with POE, 61 percent of house officers reported an increased frequency.
Physicians and nurses had markedly different views about effects of a POE system on patient care, highlighting the need to consider both perspectives when assessing the impact of POE. With this POE system, most nurses saw beneficial effects, whereas many physicians saw negative effects.
Hypertensive patients with target organ damage are at increased cardiovascular risk, and should be treated most aggressively. The association between urinary albumin excretion and left ventricular ...hypertrophy (LVH) in prior studies is inconsistent, and has not been described using a single, random spot urine specimen. Therefore, we evaluated the association between the urinary albumin creatinine ratio (ACR) and left ventricular (LV) mass and also tested the hypothesis that a simple random, single-void urine ACR would identify high risk young, hypertensive, African-American men. We measured echocardiographic LV mass and a random spot urinary ACR in 109 untreated, hypertensive, young, inner city, African-American men. The mean age was 41
± 6 years and the mean blood pressure (BP) was 157
± 19/107
± 13 mm Hg. Microalbuminuria (ACR 30 to 300 mg/g) was present in 22% of subjects. The ACR is higher in the men with LVH than in the men without LVH (
P
< .05). Increased ACR is a predictor of increased LV mass index (
P
< .003) using multiple linear regression. An ACR
>30 mg/g has a sensitivity of 33% and a specificity of 82% for the diagnosis of echocardiographic LVH. In conclusion, elevated random spot ACR is a marker of increased LV mass, independent of BP, in young urban African-American men with hypertension, and may help to determine the aggressiveness of antihypertensive therapy in this high-risk group.
As the authors acknowledge, the key question implicit in this study is whether the low use of thrombolytic therapy harms elderly patients with AMI with ST elevation. The discussion notes that Boucher ...and coworkers found a surprising overall "lack of association between thrombolytic therapy and improved in-hospital survival." Although this finding may be a result of selection bias or chance, other studies have shown consistently that selection bias actually favours thrombolytic patients, who tend to be younger and healthier than those not treated with thrombolysis. Boucher and colleagues suggest that another possible explanation for the lack of thrombolytic benefit might lie in our recent reports that showed no benefit to thrombolytic therapy for patients over the age of 75 years. In our study, the hazard ratio for 30-day survival for patients aged 65-75 years was 0.88 (95% confidence interval CI 0.69-1.12, p = 0.29), which is consonant with the results of randomized trials, whereas for patients aged 76-86 years there was a significant survival disadvantage, with a hazard ratio of 1.38 (95% CI 1.12-1.71, p = 0.003) and a particularly marked survival disadvantage among elderly women. These findings have been replicated by other investigators.3 A decade ago a randomized trial of thrombolytic therapy9 in elderly patients was stopped, largely because physicians were unwilling to assign patients randomly to nonthrombolytic therapy, an attitude that with hindsight may have been a triumph of hope over experience. Published randomized trials of thrombolytic therapy have concentrated on young cohorts of patients with AMI who have a relatively low mortality rate, whereas in community practice more than half of deaths from AMI occur in patients aged 75 years or more, a proportion that will continue to rise as the population ages. The prospect of conducting new inclusive, community-based randomized trials to determine the effectiveness of thrombolytics in elderly patients with AMI - a question deemed settled (albeit by consensus more than by proof for nearly a decade - raises the following 2 concerns: that stand-alone thrombolytic therapy may soon be superseded by other therapies, such as primary angioplasty, facilitated angioplasty or combinations of low-dose thrombolytic drugs with glycoprotein Hb/IIIa inhibitors; and that the pharmaceutical industry, without whose support randomized trials seldom occur, is unlikely to finance studies of drugs that have already been approved. These generic objections apply whenever new findings cast doubt on the effectiveness of approved drugs. But thrombolytic therapy remains the mainstay of community treatment for elderly patients with AMI associated with ST elevation, and to date trials of new therapies have provided no new guidance about effectiveness or toxicity in elderly patients. Despite the logistical difficulties involved in randomized trials in subgroup populations, trials focused specifically on the cohort with the highest mortality- the elderly population - are urgently needed."
Increasing access to the short-lived α-emitting radionuclide astatine-211 (211At) has the potential to advance targeted α-therapeutic treatment of disease and to solve challenges facing the medical ...community. For example, there are numerous technical needs associated with advancing the use of 211At in targeted α-therapy, e.g., improving 211At chelates, developing more effective 211At targeting, and characterizing in vivo 211At behavior. There is an insufficient understanding of astatine chemistry to support these efforts. The chemistry of astatine is one of the least developed of all elements on the periodic table, owing to its limited supply and short half-life. Increasing access to 211At could help address these issues and advance understanding of 211At chemistry in general. We contribute here an extraction chromatographic processing method that simplifies 211At production in terms of purification. It utilizes the commercially available Pre-Filter resin to rapidly (<1.5 h) isolate 211At from irradiated bismuth targets (Bi decontamination factors ≥876 000), in reasonable yield (68–55%) and in a form that is compatible for subsequent in vivo study. We are excited about the potential of this procedure to address 211At supply and processing/purification problems.
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