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Increased dispersion of the QT interval has been observed during pacing or exercise stress testing in patients with coronary artery disease (CAD). It has not been established whether this phenomenon is a consequence of ischemia. Therefore, we sought to evaluate whether dipyridamole-induced myocardial ischemia, as directly detected by echocardiographic monitoring of regional contractile function, would affect QT dispersion. Twenty-four patients with nonsignificant and 34 patients with significant CAD but no previous myocardial infarction underwent dipyridamole stress echocardiography while not taking medications. QT dispersion was measured on a 12-lead electrocardiogram at baseline and at various times after dipyridamole infusion. Dipyridamole infusion did not influence QT dispersion in patients without CAD. QT dispersion was similarly unaffected in patients with CAD in whom dipyridamole did not induce wall motion abnormalities. In contrast, in patients with positive dipyridamole stress test findings, QT dispersion increased from 60 +/- 17 ms at baseline to 94 +/- 25 ms during peak infusion (p <0.0001), with a time course mirroring that of development of contractile abnormalities. QT dispersion returned to 63 +/- 25 ms upon relief of ischemia by administration of aminophylline. The increase in QT dispersion was significantly related to the extent of contractile dysfunction induced by dipyridamole. Although ST-segment depression occurred in only 40% of patients with positive dipyridamole stress test findings, 88% of such patients had an increase in QT dispersion. Analysis of the receiver-operating characteristic curve showed that a QT dispersion increase of > or =20 ms identified positive findings for dipyridamole stress echocardiography with 68% sensitivity and 91% specificity. Thus, QT dispersion is acutely affected by myocardial ischemia induced by the administration of dipyridamole. Measurement of QT dispersion may improve detection of stress-induced ischemia on surface electrocardiograms. [ABSTRACT FROM AUTHOR]

The prognostic role of C-reactive protein levels in patients with a first acute myocardial infarction, an uncomplicated in-hospital course, and the absence of residual ischemia on a predischarge ergometer test and with an echocardiographic ejection fraction > or = 50% has not been described. C-reactive protein was determined during hospitalization in 64 patients (55 men, mean age 64.6 +/- 10.4 years). The patients were followed up for 13 +/- 4 months and the following cardiac events were recorded: cardiac death, new-onset angina pectoris, and recurrent myocardial infarction. Patients who developed cardiac events during the follow-up period had significantly higher C-reactive protein values than patients without events (3.61 +/- 2.83 vs 1.48 +/- 2.07 mg/dl, p <0.001). The probability of cumulative end points was: 6%, 12%, 31%, and 56% (p = 0.006; RR 3.55; confidence interval 1.56 to 8.04), respectively, in patients stratified by quartiles of C-reactive protein (< 0.45, 0.45 to 0.93, 0.93 to 2.55 and > 2.55 mg/dl). In the Cox regression model, only increased C-reactive protein levels were independently related to the incidence of subsequent cardiac events (chi-square 9.8, p = 0.001). Thus, increased C-reactive protein levels are associated with a worse outcome among patients with a first acute myocardial infarction, an uncomplicated in-hospital course without residual ischemia on the ergometer test, and with normal left ventricular function. [ABSTRACT FROM AUTHOR]

Navigating obstacles is innate to fish in rivers, but fragmentation of the world's rivers by more than 50,000 large dams threatens many of the fish migrations these waterways support. One limitation to mitigating the impacts of dams on fish is that we have a poor understanding of why some fish enter routes engineered for their safe travel around the dam but others pass through more dangerous routes. To understand fish movement through hydropower dam environments, we combine a computational fluid dynamics model of the flow field at a dam and a behavioral model in which simulated fish adjust swim orientation and speed to modulate their experience to water acceleration and pressure (depth). We fit the model to data on the passage of juvenile Pacific salmonids (Oncorhynchus spp.) at seven dams in the Columbia/Snake River system. Our findings from reproducing observed fish movement and passage patterns across 47 flow field conditions sampled over 14 y emphasize the role of experience and perception in the decision making of animals that can inform opportunities and limitations in living resources management and engineering design.

The fabrication of advanced architectures in poly(methylmethacrylate-co-styrene) (PMMA-S) copolymers (ranging from 12 to 66% mol content of methylmethacrylate) using direct laser interference patterning is reported. For all copolymer compositions, two different regimes were observed. At low laser intensities, the irradiated surfaces swell up due to the formation of microbubbles that result from the degradation of the methylmetacrylate (MMA) component. While laser ablation produces concave holes, the swelling process permits fabrication of convex hemispherical dots. At higher intensities the bubbles release from the surface forming a periodic micropored structure. In addition, the laser fluence necessary to swell the polymeric surface (swelling threshold) does not depend on polymer composition, while the ablation threshold, which determines the transition to the periodic micropored structure, strongly depends on the MMA content. This observation can be explained by the mechanical and chemical properties of the copolymer. The method provides a unique way to produce periodical structures protruding from the polymer surface.

Although there is consensus regarding the existence of childhood depression, disagreement remains as to whether symptoms are developmentally isomorphic. Previous studies focused on developmental differences in symptom levels; analyses of relations among symptoms may be more appropriate, however. Here both approaches were used to compare the Children's Depression Inventory responses from 1,030 clinic-referred children and adolescents. Four of nine symptom categories showed significant developmental differences in their correlations with total score. Externalizing behavior and guilt were more strongly related to depression in children than adolescents; affective symptoms and concerns about the future showed the reverse pattern. Results illustrate the importance of considering relations among symptoms as well as differences in symptom levels when evaluating theoretical claims about developmental differences in the nature of clinical syndromes.