Citations

Background and Purpose— With the changes in management of atrial fibrillation (AF) over time, it is possible that the time trends of post-AF stroke incidence and mortality have changed. We sought to determine whether the incidence and survival of ischemic stroke after AF diagnosis have improved. Methods— We identified the Olmsted County, Minn, residents who developed first AF from 1980 to 2000 and followed them in medical records to 2004. The outcomes were first ischemic stroke and death. Results— Of the 4117 subjects diagnosed with first AF and without previous stroke, 446 (11%) sustained a first ischemic stroke during a mean follow-up time of 5.5±5.0 years. The age- and sex-adjusted incidence of stroke decreased, on average, by 3.4% per year ( P =0.0001), concurrent with an increase in warfarin and aspirin use (both P <0.0001) and reduction of systolic blood pressure ( P <0.001). The age-adjusted ischemic stroke incidence was higher in women ( P =0.039), but not after adjusting for systolic blood pressure ( P =0.41). Compared with the general Minnesota white population, the relative mortality hazard ratio was 1.88 for men and 1.84 for women without stroke and 3.03 for men and 3.80 for women ( P <0.05) with stroke. The relative mortality hazard did not vary by age or calendar year of AF diagnosis. Conclusions— Post-AF ischemic stroke incidence decreased significantly from 1980 to 2000, during which time a substantial increase in the use of antithrombotic therapy and reduction of systolic blood pressure was evident. The relative mortality risk of stroke, however, had not improved over time.

Background and Purpose— Health economic analyses of intravenous tissue plasminogen activator (tPA) in acute ischemic stroke reveal a substantial cost savings. Unfortunately, tPA is vastly underused. The purpose of this study was to determine the economic impact of increasing tPA utilization in the United States. Methods— Annual incidence estimates of ischemic stroke in the United States and individual states were obtained. The proportion of all ischemic stroke patients who receive tPA was derived from published data. Economic analyses that report the expected annual cost savings of tPA were consulted. The analysis was conducted from the perspective of the healthcare system over a time period of 1 year. With incremental increases in the proportion of all ischemic stroke patients treated with tPA, potential cost savings were recalculated. The outcomes are expressed in dollars saved annually. Results— There are 616 000 new ischemic stroke patients annually. A $600 net cost savings is associated with each tPA-treated patient. Currently, an estimated 2% of all ischemic stroke patients receive tPA. If the proportion was increased to 4, 6, 8, 10, 15, or 20%, the realized cost savings would be approximately $15, 22, 30, 37, 55, and 74 million, respectively. Conclusions— If even small manageable increases in the proportion of all ischemic stroke patients who received tPA were achieved, it would result in an enormous realized savings for America’s healthcare system.

Abstract Rationale Standard therapy for Wegener's granulomatosis is fraught with substantial toxicity and not always effective. B lymphocytes have been implicated in the pathogenesis of Wegener's granulomatosis. Their depletion has been proposed as salvage therapy for refractory disease. Earlier encouraging reports are confounded by concomitant immunosuppressive medications and include only limited available biomarker data. Objectives To evaluate the efficacy and safety of rituximab for remission induction in refractory Wegener's granulomatosis. Methods A prospective open-label pilot trial was conducted with 10 patients monitored for 1 yr. Included were patients with active severe antineutrophil cytoplasmic antibody (ANCA)–associated vasculitis, ANCA positivity, and resistance to (or intolerance of) cyclophosphamide. The remission induction regimen consisted of oral prednisone (1 mg/kg/d) and four weekly infusions of rituximab (375 mg/m2). Prednisone was tapered and discontinued over 5 mo. Failure to achieve remission, a clinical flare in the absence of B lymphocytes, and inability to complete the glucocorticoid taper were considered treatment failures. Main Results Three women and seven men (median age, 57 yr; range, 25–72 yr) were enrolled. All had ANCA reacting with proteinase-3. The median activity score at enrollment was 6 (range, 5–10). All patients tolerated rituximab well, achieved swift B-lymphocyte depletion and complete clinical remission (activity score, 0) by 3 mo, and were tapered off glucocorticoids by 6 mo. Five patients were retreated with rituximab alone for recurring/rising ANCA titers according to protocol. One patient experienced a clinical flare after B lymphocyte reconstitution. Conclusion In this cohort, rituximab was a well-tolerated and effective remission induction agent for severe refractory Wegener's granulomatosis.

A general equation is derived that describes the behavior of a piezoelectric transducer with a nonuniform distribution of piezoelectric coefficient within its bulk, when submitted to an arbitrary distribution of acoustic pressure. Based on this equation, an expression for the receiving transfer function of the transducer is calculated. The results demonstrate the dependence of the transfer function on the distribution of piezoelectric coefficient, and that it is possible to benefit from a nonuniform distribution to optimize the transfer function. The general equation also describes the influence of the external electric circuit loading the transducer, which leads to another independent means of optimizing the transfer function. The proposed model combines effects of piezoelectric material characteristics, acoustic backing, and electric loading, without resorting to Mason or other equivalent circuits for the transducer.

The heart is a three-dimensional structure that performs its function by undergoing complex deformation. Current clinical evaluation of the heart is limited to silhouettes, outlines, projections, or tomograms, obligating the clinician or investigator to sequentially evaluate a series of two-dimensional images using mental assimulation of data. To provide more easily understandable three-dimensional images, techniques have been developed for acquiring data in sequential planes through the heart to display the beating heart in three dimensions. Analysis of such data on a user-friendly workstation can be accomplished using an extensive set of software tools developed at our institution. Three-dimensional imaging can be used as an effective means of teaching interrelationships of volume, contents, and function, in addition to the physiologic and anatomic interrelation-ships. Three-dimensional images of the beating human heart obtained in vivo using new data acquisition techniques will be shown. Evaluation of the method using balloons and excised hearts has shown that software and geometry of scanning are appropriate for high-accuracy measurements of surfaces.

The orotic acid dietary “liver lipid” model has successfully been used to study ultrasonic properties in excessively fatty rat livers [O'Brien et al., J. Acoust. Soc. Am. 83, 1159–1166 (1988)]. The model was used again in order to evaluate more fully ultrasound properties within a more condensed (2%–10%) lipid concentration range. The fatty livers were first evaluated in the intact animal (in situ) with an ultrasonic imaging system (≅ 5 MHz) and then the excised (in vitro) livers were evaluated over the 1- to 100-MHz frequency range. Water, lipid, total protein, and collagen were evaluated for each liver. Significant (p &lt; 0.001) correlations of ultrasonic properties (absorption, all attenuation, speed, and Markovian entropy) against tissue properties (water and lipid) were obtained, thus suggesting that the independent measure of texture may relate to basic ultrasonic propagation properties. [Work supported by NIH Grant CS36O29.]

In this paper, an experimental test of a theoretical model published previously is presented that describes the behavior of an acoustoelectric transducer with a nonuniform distribution of the piezoelectric coefficient within its bulk. Results of this theoretical model are first reviewed. Uniform and nonuniform piezoelectric transducers were fabricated, following a procedure described herein. The receive transfer functions of the transducers were recorded experimentally, and a comparison is made with the theoretical transfer functions predicted by the model, which shows good agreement. The transmit transfer functions of the uniform and nonuniform transducers were also measured and are reported. Numerical calculations of the different transfer functions given by the theoretical model for a uniform transducer associated with different backing materials are also presented, and the results are shown to be equivalent to the results following from the Mason equivalent circuit. Comparisons with experimental results and with Mason’s equivalent circuit verified the new theoretical model.

Surgical removal of gallstones is performed about 500 000 times per year in the United States. Although the usual cost ranges from $5000 to more than $10 000 per patient, the operative mortality is less than 1% for otherwise healthy persons. Nonsurgical dissolution of gallstones is often possible, but many gallstones contain calcium compounds that slow or prevent dissolution using the direct content cholesterol solvent, methyl tertbutyl ether (MTBE). Extracorporeal shock wave lithotripsy (ESL) has potential clinical utility for facilitating dissolution and possibly allowing spontaneous or induced passage of small fragments via the bile ducts and intestines. Obstacles to be overcome include predictable fragmentation of multiple stones up to 3 cm in diameter so that all particles are small enough to be rapidly dissolved or pass safely through the bile ducts (⩽ 3 mm). This must be achieved using biologically tolerable shock wave dosages without requiring general anesthesia within one or two treatment sessions. Acute and chronic safety, patient acceptance, and cost must be competitive with surgical treatment. Initial experience suggests that only solitary noncalcified stones (10% of patients with stones) have a high probability of success using ESL plus oral bile acid dissolution therapy. Improving ESL technology and direct contact fragment dissolution using MTBE should increase the clinical utility of shock wave lithotripsy of gallstones.

A nonlinear model of the human aural system is proposed. Utilizing a homomorphic transformation, the model is implemented in a digital computer and accounts for the Fletcher critical bands in hearing, the nonlinear relationship between input sound intensity and perceived loudness known as recruitment, as well as the thresholds of audibility and the maximum tolerance threshold. The transformed or output signal domain is identified as a perceptual space. It is shown that the model can be used to reproduce the Fletcher Munson equal loudness contours for normal hearing populations. Modification of easily measured parameters results in the generation of equal loudness contours for hearing impaired individuals. Through a combination of the forward homomorphic transformation for normal hearing to the perceptual domain and the inverse mapping utilizing parameters of a hearing impaired individual, it is shown that hearing intelligibility is dramatically improved. It is postulated that signal processing performed in the perceptual domain will produce results more pleasing and intelligible to the listener. Results of auditory testing utilizing the proposed model for both normal and hearing impaired populations are presented. Speech intelligibility scores are shown to increase by more than 40% (i.e., from 40% to over 80%) over preprocessed scores under headphones for hearing impaired subjects used in these tests.

Research suggests that negative affect is an important mediator in the relationship between body dissatisfaction and bulimic symptoms. This study examines the mediational role of specific emotion regulation processes (i.e., negative emotionality, poor awareness of emotion, nonconstructive coping with negative emotion) in bulimic symptoms. In addition to these emotion regulation variables, body dissatisfaction and bulimic symptoms were assessed in 234 girls in Grades 6 to 8 (mean age = 12 years, 11 months). The results indicated that negative affect, poor awareness of emotion, and nonconstructive coping with negative emotion partially mediated the relationship between body dissatisfaction and bulimic behaviors. The findings are discussed in light of previous research that suggests emotion regulation needs to be viewed as a multidimensional construct.