Diagnosis of anthracycline-induced late cardiomyopathy by exercise-spiroergometry and stress-echocardiography.

UNLABELLED: Anthracyclines are used in the therapy of several of the most common paediatric oncological disorders. The usefulness of these agents is limited by cardiotoxicity, with congestive heart failure developing in up to 20% of patients. To stratify possible risk factors, we investigated 38 children with acute lymphoblastic leukaemia for signs of late cardiomyopathy. Exercise-spiroergometry and stress-echocardiography with measurement of fractional shortening (FS) and ejection fraction (EF) as indicators of left ventricular function were performed. ECG, 24 h Holter monitoring, chest X-ray, virus serology and carnitine were analysed. Control subjects were 38 healthy children matched for age and body surface area. All 38 patients had normal echocardiographic findings at rest (EF: 0.73 +/- 0.06; FS: 0.35 +/- 0.05). ten patients had a significant attenuation of left ventricular function after exercise assessed by stress-echocardiography compared to the remaining 28 patients and 38 healthy control subjects (EF: 0.52 +/- 0.08 versus 0.77 +/- 0.06 and 0.80 +/- 0.08; FS: 0.29 +/- 0.06 versus 0.39 +/- 0.05 and 0.41 +/- 0.02); patients with reduced ventricular function after exercise had significant low anaerobic threshold, subnormal maximal oxygen uptake and decreased carnitine levels. The findings were not related to the dosage of administered doxorubicin. There exists no correlation between ECG, 24 h ECG, chest X-ray, virology and left ventricular dysfunction. The benefit of angiotensin converting enzyme inhibitors and the administration of carnitine remains speculative. CONCLUSION: exercise-spiroergometry and stress-echocardiography are sensitive investigations for diagnosing subclinical cardiomyopathy late after completion of chemotherapy. Investigative findings of cardiomyopathy are not dose related and may provide information for therapeutic prevention before clinical symptoms of cardiomyopathy appear.

Visual marking and the perception of salience in visual search.

In the present study, the gap paradigm originally developed by Watson and Humphreys (1997) was used to investigate whether the process of visual marking can influence the perceptual salience of a target in visual search. Consistent with previous studies (Watson & Humphreys, 1997), the results showed that search was not affected by the presence of the preceding distractors when the target was relatively low in salience. This finding suggests that visual marking can increase the efficiency of visual search by decreasing the size of the search set. However, more important, the results also showed that search was affected by the presence of the preceding distractors when the target was relatively high in salience. This finding suggests that visual marking may be limited in its ability to increase the perceptual salience of the target. Together, the results of the present study suggest that the effectiveness of visual marking may vary as a function of search context.

Inhibition of return and attentional control settings.

In the present study, we used a spatial cuing paradigm in conjunction with a choice identification task to investigate whether exogenous attentional orienting and inhibition of return are affected by attentional control settings. As in previous studies (e.g., Folk, Remington, & Johnston, 1992), onset- and color-defined targets were crossed with uninformative onset- and color-defined cues. As expected, when the cue-target stimulus onset asynchrony (SOA) was short (i.e., 100 msec), the results showed that exogenous attentional orienting was contingent on attentional set; attentional capture occurred in response to a particular cue only when the feature that defined the cue also defined the target (Folk et al., 1992). More importantly, when the cue-target SOA was long (i.e., 1,000 msec), the results showed that the occurrence of inhibition of return was also contingent on attentional set, at least partially so; inhibition of return occurred in response to onset cues only when they preceded onset targets. In contrast, inhibition of return never occurred in response to color cues (at a variety of long SOAs). The associations and dissociations that were observed between exogenous attentional orienting and inhibition of return are discussed in terms of posterior and anterior attention networks in the brain (Posner & Petersen, 1990).

Searching for one versus two identical targets: when visual search has a memory.

A recent study has suggested that observers' visual explorations of the external world can proceed unimpaired when the visual environment precludes the operation of memory processes (as, for instance, when the display elements change locations every 100 ms). One theoretical limitation of this study was that distractors were the only elements that had the potential to be tagged during visual search. The present study sought to clarify the amnesic-search hypothesis by investigating whether memory processes can guide search in other contexts in which targets also have the potential to be tagged. Accordingly, the experimental conditions of the previous study were repeated using a different search task in which observers had to decide whether one target or two were present among a variable number of similar distractors. Under these search conditions, the present findings provided strong evidence that memory processes can guide visual search.

Stimulus-driven attentional capture is contingent on attentional set for displaywide visual features.

This research showed that the current criterion for stimulus-driven attentional capture is not sufficient to rule out goal-directed processes that are critical for producing attentional capture. This was shown by demonstrating a contingency between displaywide visual features (i.e., features that signal the appearance of the task-relevant target display as a whole) and the features that capture attention. In Experiment 1, the target display was signaled by both color and onset; in Experiment 2, the target display was signaled only by onset. As expected, Experiment 1 showed that task-irrelevant color and onset distractors both captured attention, whereas Experiment 2 showed that only onset distractors captured attention. These contingencies suggest that the strongest evidence currently available for stimulus-driven attentional capture may be caused by goal-directed processes.

Visual quality and attentional capture: a challenge to the special role of abrupt onsets.

This article investigates the nature of stimulus-driven attentional capture. Previous studies (e.g., J. Jonides & S. Yantis, 1988) have suggested that only a single visual feature--abrupt visual onset--can elicit stimulus-driven attentional capture. Two experiments are reported that challenge the special status of abrupt onsets in attentional capture. In particular, this evidence suggests that abrupt onsets appear to attenuate display-size effects only in certain experimental contexts that inadvertently increase the ease with which they are perceived. Consequently, the special status attributed to abrupt onsets is argued to derive from their higher visual quality.

Inhibition and disinhibition of return: evidence from temporal order judgments.

In the present study the temporal order judgment (TOJ) task was used to investigate whether or not inhibition of return (IOR) affects perceptual processing. Previous failures to obtain IOR in the TOJ task have been taken to suggest that IOR does not affect perceptual processing (e.g., Maylor, 1985). The present study showed that IOR is modulated by the temporal disparity between successive targets as well as the relative order in which they appear at cued and uncued locations. Consequently, IOR affects TOJs in some conditions but not in others. The selective occurrence of IOR in the TOJ task provides converging support for the notion that IOR does affect perceptual processing, and also accounts for the previous failures to observe IOR in the TOJ task. Moreover, these and other results suggest that inhibitory processing at the cued location can be disinhibited when stimulation occurs at other locations.

Object recognition contributions to figure-ground organization: operations on outlines and subjective contours.

In previous research, replicated here, we found that some object recognition processes influence figure-ground organization. We have proposed that these object recognition processes operate on edges (or contours) detected early in visual processing, rather than on regions. Consistent with this proposal, influences from object recognition on figure-ground organization were previously observed in both pictures and stereograms depicting regions of different luminance, but not in random-dot stereograms, where edges arise late in processing (Peterson & Gibson, 1993). In the present experiments, we examined whether or not two other types of contours--outlines and subjective contours--enable object recognition influences on figure-ground organization. For both types of contours we observed a pattern of effects similar to that originally obtained with luminance edges. The results of these experiments are valuable for distinguishing between alternative views of the mechanisms mediating object recognition influences on figure-ground organization. In addition, in both Experiments 1 and 2, fixated regions were seen as figure longer than nonfixated regions, suggesting that fixation location must be included among the variables relevant to figure-ground organization.

Object continuity in apparent motion and attention.

Recent theories of attention have emphasized the role of object-based representations in visual selection. One defining property of any object is spatiotemporal continuity. The present experiments show that the continuity property may underlie two seemingly unrelated perceptual phenomena: attentional capture by abrupt visual onset and the appearance of bistable apparent motion displays. In Experiment 1, observers carried out two visual tasks. In the first task, they reported the appearance of a bistable apparent-motion (or Ternus) display. Whether group or element motion was perceived depended on the duration of the blank interval between successive frames. In the second task, subjects engaged in visual search for a prespecified target, and one each trial one element was briefly flickered off and back on. The degree to which that element captured attention also depended on the duration of the temporal gap. The time course of the gap duration effect in the visual search task was very similar to that for the Ternus display. In Experiment 2, we ruled out the possibility that the presence of an abrupt offset caused the results of Experiment 1. It is argued that the apparent motion and attentional capture phenomena examined here may reflect the operation of the same underlying mechanism: in both cases, a sufficiently long temporal gap disrupts spatiotemporal continuity, thereby fundamentally changing the perceived organization of the display.

Does orientation-independent object recognition precede orientation-dependent recognition? Evidence from a cuing paradigm.

Object recognition may entail an incremental normalization process before access to canonical orientation representations, but is this process guided by prior access to object-centered representations? In Experiment 1, the authors showed observers figure-ground stimuli known to reflect access to, and output from, stored shape representations. The stimuli appeared in each of 6 different orientations, preceded by cues providing either (a) no information, (b) upright shape information only, (c) upright shape information plus orientation information (separately), or (d) shape information in the same orientation as the upcoming figure-ground test stimulus. Contrary to predictions by a postaccess account, the cues failed to eliminate orientation dependency in shape recognition. The results favor a preaccess account of the normalization process within the context of canonical orientation representations.

Inhibition of return to object-based and environment-based locations.

Inhibition of return (IOR) has been described in terms of two functional components. The location-based component is associated with descriptions of spatially fixed, environmental locations; the object-based component is associated with more abstract descriptions of spatially invariant objects. In the present study, we hypothesized that the location-based component may also be associated with descriptions of spatially invariant objects because, like environment-based descriptions, object-based descriptions have an intrinsic spatial structure. To test this hypothesis, we employed a computer-generated depiction of a brick that rotated in depth between the presentations of cue and target. The results of four experiments showed that IOR accrued to locations that remained fixed with respect to the brick as well as the environment, suggesting that both object-based and environment-based descriptions can influence location-based IOR.

Visual attention and objects: one versus two or convex versus concave?

According to object-based theories of visual attention, attention can be divided within a single object more efficiently than between separate objects (J. Duncan, 1984). Recently, G. C. Baylis and J. Driver (1993) provided a theoretical framework for interpreting this single-object advantage within the domain of spatial organization. Using their hierarchical coding of location hypothesis, they showed that the latency to compare the location of 2 vertices was significantly faster for vertices that were seen as part of a single (convex) object than for vertices that were seen as parts of separate (concave) objects. This article reports the replication of this finding, as well as new evidence that shows that latency is affected by the convexity of the contour, and not by the number of objects.

Antibiotic sensitivity of bacteria from urine.

Bacteria isolated from the urine of 400 hospital inpatients and 483 outpatients were identified and the in vitro sensitivity of these organisms against 12 antibacterial agents currently used in the treatment of urinary tract infections was determined. There was little difference in the distribution of organisms between the two groups. Escherichia coli was predominant, accounting for 58% of the inpatients and 66% of the outpatients. Klebsiella was present in 15% of the inpatients as against 7% in the outpatients. Proteus mirabilis 9% inpatients and 8% outpatients and Enterococcus, 7% inpatients and 5% outpatients made up most of the remainder. The different organisms showed varying sensitivity patterns to the antibiotics tested. The commonly used antibiotics with the broadest spectrum were cephalexin and cotrimoxazole.