What Is Going on with Visual Attention in Reading and Dyslexia? A Critical Review of Recent Studies.

This critical review examined current issues to do with the role of visual attention in reading. To do this, we searched for and reviewed 18 recent articles, including all that were found after 2019 and used a Latin alphabet. Inspection of these articles showed that the Visual Attention Span task was run a number of times in well-controlled studies and was typically a small but significant predictor of reading ability, even after potential covariation with phonological effects were accounted for. A number of other types of tasks were used to examine different aspects of visual attention, with differences between dyslexic readers and controls typically found. However, most of these studies did not adequately control for phonological effects, and of those that did, only very weak and non-significant results were found. Furthermore, in the smaller studies, separate within-group correlations between the tasks and reading performance were generally not provided, making causal effects of the manipulations difficult to ascertain. Overall, it seems reasonable to suggest that understanding how and why different types of visual tasks affect particular aspects of reading performance is an important area for future research.

The distribution of spatial attention changes with task demands during goal-directed reaching.

Goal-directed movements are commonly used to allow humans to interact with their environment. When making a goal-directed movement in a natural environment, there are many competing stimuli. It is therefore important to understand how making a goal-directed movement could be impacted by the need to divide attention between the movement and competing stimuli. We used a dual-task paradigm to investigate the sharing of attentional resources between a search task in central vision and a peripheral pointing task completed concurrently. Results suggest some degree of shared attentional resources between these two tasks with performance on both central and peripheral tasks degraded under dual-task conditions. Movement latency, but not movement time, was also affected by dual-task conditions. Altogether, the results suggest that there is a cost to reach performance if attention is engaged away from the movement goal. Interestingly, this cost is associated with movement planning rather than execution.

Potential clinical utility of partial body weight support on treadmill walking time in persons with intermittent claudication: a single case report.

Intermittent claudication can seriously limit an individual's walking capacity. Walking programs are known to improve this limitation but could be limited by a person's ability to carry his or her own full body weight to perform the walking. We theorized that decreasing body weight, through mechanical unloading, might allow longer pain-free walking, thus potentially accelerating exercise training. This case report describes the effect of partial body weight support (PBWS) on walking time in a patient with claudication. A 60-year-old male with calf pain that prevented him from walking long distances or walking quickly was studied. The patient completed three treadmill walking tests (0%, 25%, and 50% PBWS) until claudication pain stopped him or 15 minutes elapsed. The participant walked 4:31 minutes at 0% PBWS with a pain rating of 3/4. He walked the full 15 minutes under each support condition with the same or less claudication pain (3/4 for 25% PBWS, 2/4 for 50% PBWS). This case reports the successful use of PBWS treadmill training for increasing walking time in an individual with intermittent claudication. If this finding holds true for a larger sample, PBWS may be a way for these individuals to participate in exercise training programs with less pain.

Initial cytoplasmic and phagosomal consequences of human neutrophil exposure to Staphylococcus epidermidis.

Microorganisms are recognized by specific phagocyte surface receptors. Liganded receptors then signal a series of events leading to phagocytosis and destruction of the organism by oxidative, lytic, and associated processes. Some organisms, such as Mycobacterium tuberculosis (Mtb), Cryptococcus neoformans (Cf), and others, evade such destruction, surviving and sometimes multiplying within the phagosome to later cause disease. To study such evasion, we developed protocols which permit simultaneous kinetic measurement of early cytoplasmic signaling and of phagosomal pH (pH(p)) and oxidative burst, on a cell-by-cell basis, of polymorphonuclear (PMN) leukocytes exposed to fluorescently labeled, nonpathogenic Staphylococcus epidermidis (Se). The availability of a new, highly sensitive pH probe, pHrodo, permits observation of increasing pH(p). Simultaneous labeling of the organism, applicable to any phagocyte target, with a probe insensitive to pH and oxidative species, such as AlexaFluor350, permits distinction between binding and functional responses to it by ratioing fluorescences. Addition of an extracellular-specific quencher (Trypan blue) permits distinction between bound and phagosome-enclosed targets, so that conditions within the closed phagosome can be studied. We found that opsonization is required for functional activation of PMN by Se, that the organism causes early alkalinization of the phagosome (in contrast to Cf which hyperacidifies it), and that extracellular Ca(2+) is not required for cytoplasmic Ca(2+) signaling but contributes markedly to binding of Se to PMN and to ensuant bactericidal functions. These findings lead to a new approach to the study of select organisms, like Cf and Mtb, which evade killing by manipulating the phagosomal environment.

Sequential chemotactic and phagocytic activation of human polymorphonuclear neutrophils.

Human polymorphonuclear neutrophils (PMN) chemotax to a foreign entity. When the chemoattractants' origins are reached, specific receptors bind to the invader's surface, initiating phagocytosis, phagosome formation, and fusion with granule membranes, generating the bactericidal oxidative burst, and releasing lytic enzymes, specific peptides, and proteins. We explored the initial signaling involved in these functions by observing naïve, unprimed PMN in suspension using fluorescent indicators of cytoplasmic signals (Delta[Ca(2+)](i) and DeltapH(i)) and of bactericidal entities (oxidative species and elastase) exposed to N-formyl-methionyl-leucyl-phenylalanine (fMLP) and/or multivalent immune complexes (IC). fMLP and IC each initiate a rapid transient rise in [Ca(2+)](i), mostly from intracellular stores, simultaneously with a drop in pH(i); these are followed by a drop in [Ca(2+)](i) and a rise in pH(i), with the latter being due to a Na(+)/H(+) antiport. The impact of a second stimulation depends on the order in which stimuli are applied, on their dose, and on their nature. Provided that [Ca(2+)](i) is restored, 10(-7) M fMLP, previously shown to elicit maximal Delta[Ca(2+)](i) but no bactericidal functions, did not prevent the cells' responses with Delta[Ca(2+)](i) to a subsequent high dose of fMLP or IC; conversely, cells first exposed to 120 mug/ml IC, previously shown to elicit maximal Delta[Ca(2+)](i) and bactericidal functions, exhibited no subsequent Delta[Ca(2+)](i) or DeltapH(i) to either stimulus. While exposure to 10(-7) M fMLP, which saturates the PMN high-affinity receptor, did not elicit bactericidal release from these naïve unprimed PMN in suspension, 10(-5) M fMLP did, presumably via the low-affinity receptor, using a different Ca(2+) source.

Predictive validity of neuropsychiatric subgroups on nursing home placement and survival in patients with Alzheimer disease.

OBJECTIVE: The aim of the study was to conceptualize neuropsychiatric symptoms in patients with Alzheimer disease as distinct symptom profiles with differential disease outcomes. Two outcomes of interest in the study were nursing home placement and survival. METHOD: Cluster analysis was used to categorize 122 patients with Alzheimer disease based on their neuropsychiatric symptoms as assessed by the Neuropsychiatric Inventory. Both the presence as well as the severity and frequency of symptoms were considered. After identification of the subgroups, the predictive validity of the categorization was tested on time to nursing home placement and time to death over a three-year period. Cox proportional hazard models were used to perform survival analysis. Important covariates such as severity of cognitive and functional impairments, comorbid medical conditions, presence of parkinsonism, and marital status were adjusted at baseline. RESULTS: Based on the presence of neuropsychiatric symptoms, three subgroups were identified: minimally symptomatic, highly symptomatic, and affective/apathetic. Over a three-year period, the highly symptomatic group had an increased risk of nursing home placement. In addition, the rates of survival were significantly lower for the highly symptomatic and the affective/apathetic subgroups. Based on the severity and frequency of symptoms, two-cluster and four-cluster solutions were produced. The groupings based on severity and frequency of symptoms predicted significant differential outcomes in survival and nursing home placement. CONCLUSIONS: Neuropsychiatric subgroups were able to predict differential outcomes and identify those with an increased risk for a worse prognosis. The findings were discussed through their research and clinical implications.

Simultaneous measurements of cytoplasmic Ca2+ responses and intracellular pH in neutrophils of localized aggressive periodontitis (LAP) patients.

In view of the reports that polymorphonuclear leukocytes (PMN) of patients with localized aggressive periodontitis (LAP) exhibit hyper-responsiveness to stimulation, it has been suggested that such abnormalities could lead to PMN-mediated tissue damage during inflammation. To determine whether these abnormalities include signal transduction, we compared cytoplasmic calcium concentration (Delta[Ca2+](i)) and cytoplasmic pH (DeltapH(i)) changes, early stimulus responses to chemotactic agents, of LAP versus control (C)-PMN and explored whether these could be modulated by sensitizing cytokines or calcium channel-blocking agents. PMN responses of LAP patients were compared with age- and gender-matched controls. Delta[Ca2+](i) and DeltapH(i) were measured fluorimetrically using 1H-indole-6-carboxylic acid, 2-[4-[bis[2-[(acetyloxy)methoxy]-2-oxoethyl]amino]-3-[2-[2-[bis[2-[(acetyloxy)methoxy]-2-oxoethyl]amino]-5-methylphenoxy]ethoxy]phenyl]-1 and 2',7'-bis-(carboxyethyl)-5(6)-carboxyfluorescein as respective probes. Not only was the maximal calcium response to chemoattractants higher in LAP-PMN, but also their subsequent intracellular calcium redistribution was significantly slower. The slower calcium redistribution of LAP-PMN, but not their higher maximal calcium response, was successfully mimicked in C-PMN treated with Nifedipine or 1-[b-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole-HCl, both known to be inhibitors of membrane-associated calcium influx, but this redistribution was not affected when inhibitors of other calcium influx mechanisms, Diltiazem or Verapamil, were used. Taken together, our findings indicate that certain early stimulus responses are aberrant in LAP-PMN, that internal redistribution of cytoplasmic-free calcium is compromised, and, additionally, that a membrane-associated Ca2+ transport defect may be present.

Immune complex stimulation of human neutrophils involves a novel Ca2+/H+ exchanger that participates in the regulation of cytoplasmic pH: flow cytometric analysis of Ca2+/pH responses by subpopulations.

The activation of human phagocytic leukocytes by immune complexes (IC) or opsonized microbes via their Fc and complement receptors has been well-described. The mechanisms involved in this process are complex and depend on the receptors involved. The biochemical events that lead to the destruction of invading organisms in turn display varying degrees of interdependence, but the controlling elements that lead to the ultimate killing of ingested organisms within phagosomes by lysosomal enzymes and reactive oxygen intermediates are still not completely understood. We have addressed these mechanisms by following and correlating the kinetics of responses by individual cells, using multiparameter flow cytometry. Using nonopsonized IC as stimuli, we document here the presence of a novel Ca(2)(+)/H(+) voltage-independent channel in human neutrophils, which helps to control their cytoplasmic pH.