Increased serum C-reactive protein concentrations in dogs with congestive heart failure due to myxomatous mitral valve disease.

Cardiovascular disease in humans and dogs is associated with mildly increased circulating concentrations of C-reactive protein (CRP). Few studies have evaluated associations between circulating CRP and canine myxomatous mitral valve disease (MMVD) and the results reported have been divergent. The aim of this study was to investigate whether serum concentrations of CRP, determined using a novel automated canine-specific high-sensitivity CRP assay (Gentian hsCRP), were associated with severity of MMVD and selected clinical variables in dogs. The study included 188 client-owned dogs with different severities of MMVD. Dogs were classified based on ACVIM consensus statement guidelines (group A, n = 58; group B1, n = 56; group B2, n = 38; group C, n = 36). Data were analysed using descriptive statistics and multiple regression analysis. Dogs with congestive heart failure (CHF; group C) had significantly higher CRP concentrations (median, 2.65 mg/L; quartile 1-quartile 3, 1.09-5.09) compared to dogs in groups A (median, 0.97 mg/L; quartile 1-quartile 3, <0.50-1.97; P = 0.001), B1 (median, 0.78 mg/L; quartile 1-quartile 3, <0.50-1.73, P <0.0001) and B2 (median, 0.60 mg/L; quartile 1-quartile 3, <0.50-1.23; P <0.0001). Other variables reflecting disease severity, including left atrial to aortic root ratio (P = 0.0002, adjusted r(2) = 0.07) and left ventricular end-diastolic diameter normalised for bodyweight (P = 0.0005, adjusted r(2) = 0.06), were positively associated with CRP concentration, but the association disappeared if dogs with CHF were excluded from analysis. In conclusion, slightly higher CRP concentrations were found in dogs with CHF whereas severity of asymptomatic MMVD showed no association with CRP concentrations.

Missense mutation in PFKM associated with muscle-type phosphofructokinase deficiency in the Wachtelhund dog.

Hereditary muscle-type phosphofructokinase (PFK) deficiency causing intermittent hemolytic anemia and exertional myopathy due to a single nonsense mutation in PFKM has been previously described in English Springer and American Cocker Spaniels, Whippets, and mixed breed dogs. We report here on a new missense mutation associated with PFK deficiency in Wachtelhunds. Coding regions of the PFKM gene were amplified from genomic DNA and/or cDNA reverse-transcribed from RNA of EDTA blood of PFK-deficient and clinically healthy Wachtelhunds and control dogs. The amplicons were sequenced and compared to the published canine PFKM sequence. A point mutation (c.550C>T, in the coding sequence of PFKM expressed in blood) was found in all 4 affected Wachtelhunds. This missense mutation results in an amino acid substitution of arginine (Arg) to tryptophan (Trp) at position 184 of the protein expressed in blood (p.Arg184Trp). The mutation is located within an alpha-helix, and based on the SIFT analysis, this amino acid substitution is not tolerated. Amplifying the region around this mutation and digesting the PCR fragment with the restriction enzyme MspI, produces fragments that readily differentiate between PFK-deficient, carrier, and normal animals. Furthermore, we document 2 additional upstream PFKM exons expressed in canine testis but not in blood. Despite their similar phenotypic appearance and use for hunting, Wachtelhunds and English Springer Spaniels are not thought to have common ancestors. Thus, it is not surprising that different mutations are responsible for PFK deficiency in these breeds. Knowledge of the molecular basis of PFK deficiency in Wachtelhunds provides an opportunity to screen and control the spread of this deleterious trait.

Repetition effects in visual search.

Maljkovic and Nakayama (1994) demonstrated an automatic benefit of repeating the defining feature of the target in search guided by salience. Thus, repetition influences target selection in search guided by bottom-up factors. Four experiments demonstrate this repetition effect in search guided by top-down factors, and so the repetition effect is not merely part of the mechanism for determining what display elements are salient. The effect is replicated in singleton search and in three situations requiring different degrees of top-down guidance: when the feature defining the target is less salient than the feature defining the response, when there is more than one singleton in the defining dimension, and when the target is defined by a conjunction of features. Repetition does not change the priorities of targets, relative to distractors: Display size affects search equally whether the target is repeated or changed. More than one mechanism may underlie the repetition effect in different experiments, but assuming that there is a unitary mechanism, a short-term episodic memory mechanism is proposed.

Contingent capture for onsets and offsets: attentional set for perceptual transients.

Four experiments were conducted to examine whether attentional set affects the ability of visual transients (onsets and offsets) to capture attention. In the experiments, visual search for an identity-defined target was conducted. In the first 3 experiments, the target display either onset entirely or was revealed by offsetting camouflaging line segments to reveal letters. Prior to the target display, there was a noninformative cue, either an onset or an offset, at one of the potential target locations. Cues that shared the same transient feature as the target display captured attention. The lack of predictable target transients led to attentional capture by all forms of transients. The final experiments with luminance changes without offsets or onsets showed attentional capture when the luminance changes were large. The results suggest that attentional set can be broadly or narrowly tuned to detect changes in luminance.

Decomposing visual search: evidence of multiple item-specific skills.

Four experiments demonstrated that visual search can be decomposed into two components: one consisting of skills shared with memory search and the other consisting of skills not shared with memory search. A training-transfer paradigm was used to test for transfer from memory search to visual search and vice versa. When the same targets and distractors were used in training and transfer, visual search practice completely trained memory search, but memory search practice only partially trained visual search. Learning on both the shared and the private components of visual search benefited more from item-specific training than from nonspecific training. The relationship between the components and some theorized models of visual search are discussed, particularly in terms of prioritization learning.

Process dissociation, cognitive architecture, and response time: comments on Lindsay and Jacoby (1994)

Process dissociation is based on 2 assumptions about the processes being dissociated: invariance of the processes across situations, and stochastic independence of the processes. In a recent application of process dissociation to the Stroop task (D. S. Lindsay & L. L. Jacoby, 1994), both of those assumptions were violated. It is argued that these violations were due to (a) an oversimplification of the processing architecture that ignores common stages such as guessing and response selection, (b) an assumption that the more automatic process (word reading) dominates over the intended process (color naming) in determining responses, and (c) an assumption that switching from the more common speeded response instruction (measuring speed) to a deadline response instruction (measuring accuracy) does not change processing. General implications for applying process dissociation to dynamic tasks are discussed.

Visual motion and attentional capture.

Previous work has shown that abrupt visual onsets capture attention. This occurs even with stimuli that are equiluminant with the background, which suggests that the appearance of a new perceptual object, not merely a change in luminance, captures attention. Three experiments are reported in which this work was extended by investigating the possible role of visual motion in attentional capture. Experiment 1 revealed that motion can efficiently guide attention when it is perfectly informative about the location of a visual search target, but that it does not draw attention when it does not predict the target's position. This result was obtained with several forms of motion, including oscillation, looming, and nearby moving contours. To account for these and other results, we tested a new-object account of attentional capture in Experiment 2 by using a global/local paradigm. When motion segregated a local letter from its perceptual group, the local letter captured attention as indexed by an effect on latency of response to the task-relevant global configuration. Experiment 3 ruled out the possibility that the motion in Experiment 2 captured attention merely by increasing the salience of the moving object. We argue instead that when motion segregates a perceptual element from a perceptual group, a new perceptual object is created, and this event captures attention. Together, the results suggest that motion as such does not capture attention but that the appearance of a new perceptual object does.

Stimulus-driven attentional capture: evidence from equiluminant visual objects.

Previous work has shown that abrupt visual onsets capture attention. Possible attention. Possible mechanisms for this phenomenon include (a) a luminance-change detection system and (b) a mechanism that detects the appearance of new perceptual objects. Experiments 1 and 2 revealed that attention is captured in visual search by the appearance of a new perceptual object even when the object is equiluminant with its background and thus exhibits no luminance change when it appears. Experiment 3 showed that a highly salient luminance increment alone is not sufficient to capture attention. These findings suggest that attentional capture is mediated by a mechanism that detects the appearance of new perceptual objects.