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S Hale

Publications and source records attributed to S Hale.

At least 37 records · Page 2Linked to original sources
PubMed1995

Converging evidence for domain-specific slowing from multiple nonlexical tasks and multiple analytic methods.

Older and young adults were tested on eight nonlexical tasks that overlapped extensively in complexity: disjunctive choice reaction time, line-length discrimination, letter classification, shape classification, mental rotation, visual search, abstract matching, and mental paper-folding. Performance on the first seven tasks was associated with equivalently low error rates in both groups, making it possible to directly compare their response times (RTs) on these tasks. Consistent with domain-specific slowing, the relationship between the RTs of the older adults and the RTs of the young adults was well described by a task-independent mathematical (Brinley) function. Evidence from this analysis and from analyses based on task-specific information-processing models leads to similar conclusions and provides converging support for general cognitive slowing in the nonlexical domain.

Adult↗
PubMed1994

The rise and fall in information-processing rates over the life span.

We surveyed studies that measured information-processing durations in groups of experimental subjects (children or elderly adults) and a group of college-aged control subjects. Some studies varied the type of processing while keeping the age of a subject group fixed. Process-durations in experimental subjects could be described by a multiplicative function of the control durations, regardless of the type of processing. Other studies varied the age of the subject groups while keeping the type of processing fixed. Process-durations declined during childhood, in a manner that could be described by a negative exponential function of age. Process-durations increased throughout middle- and old-age, in a manner that could be described by a positive exponential function of age. The sum of the two exponentials defined a U-shaped function that described process-durations over the life span. The most important studies varied both the type of processing and the age of the subject groups. An array of measurements of this kind could be described by a two-dimensional function that combined the multiplicative effect of process-duration and the exponential effects of age. The multiplicative effect of process-duration suggested that the execution of a processing sequence was conditioned by a single developmental parameter in both the experimental subject and the control subject. The exponential components determined the magnitude of the developmental parameter as the age of the subject changed. Given the global character of these effects, it seemed to us that the developmental mechanism may operate at a more elementary level than the information-processing stages conceived by cognitive theories. In a developmental framework, information processing may be reducible to a large number of small steps of a homogeneous duration or reliability, such as might be realized on a neural network. The exponential rate constants may be related to constant-probability hazards that act on one or another population of neural elements to create minute defects or incremental improvements. Their cumulative effects alter the functioning of the network over its lifetime, in a way that parallels the observed changes in process-durations.

Adolescent↗
PubMed1994

Brinley plots, explained variance, and the analysis of age differences in response latencies.

Critics of Brinley plot analyses (e.g., Fisk, Fisher, & Rogers, 1992; Perfect, 1994) claim: (a) that lack of overlap between latencies on different tasks inflates r2 values; (b) that Brinley plots mask task-specific age differences; and (c) that measurement error in young adults' latencies precludes the use of regression techniques with Brinley plot data. We dispute these claims. We show that lack of overlap does not inflate r2 and that the possible presence of task-specific effects in Brinley plot data may be evaluated using standard regression techniques. These techniques are illustrated using data from the Fisk and Rogers (1991) study of visual and memory search. Analysis of their data reveals significant differences between the lexical and nonlexical domains, but not between types of search. Finally, the effect of measurement error on Brinley plot analyses is shown to be small and, if taken into account, leads to increased support for general cognitive slowing.

Adolescent↗
PubMed1994

Cardiovascular applications of fluorocarbons in regional ischemia/reperfusion.

Potential cardiovascular therapeutic uses for perfluorochemicals include oxygen delivery distal to an occluding balloon during high risk coronary angioplasties, treatment for acute myocardial infarction with or without concomitant reperfusion, cardioplegia, and preservation of donor hearts for transplant. Infusions of oxygenated perfluorochemicals during brief coronary occlusions, as occurs with angioplasties, preserves cardiac ultrastructure and cardiac function. Fluosol is currently approved in the U.S. for angioplasty procedures. Experimental studies have suggested that perfluorochemicals reduce myocardial infarct size during permanent coronary occlusion or temporary coronary occlusion. One school of thought suggests that these agents work by reducing reperfusion injury. By inhibiting neutrophil function, including adherence to endothelial cells and release of toxic substances, perfluorochemicals may preserve the endothelium and prevent no-reflow. However, one might argue that any agent which reduces infarct size by any mechanism would result in less neutrophil infiltration and smaller no-reflow areas. One pilot study suggested that intracoronary Fluosol administered at the time of reperfusion, reduced infarct size and improved regional ventricular function in patients. However, preliminary results of a large multicenter study in which this agent was given along with thrombolysis, were largely negative. Whether perfluorochemicals will become an important adjunctive agent along with reperfusion for acute myocardial infarction remains to be determined.

Angioplasty, Balloon, Coronary↗
PubMed1993

Purification and immunological characterization of acid beta-galactosidase from dog liver.

1. Dog liver acid beta-galactosidase was isolated in high yield and purified to homogeneity using a series of chromatographies on Con A-Sepharose, decyl-agarose, anion-exchange HPLC and gel-filtration HPLC. 2. Non-denaturing gel filtration by HPLC gave a single homogeneous peak corresponding to molecular mass of 180-190 kDa. During SDS-PAGE analysis, the single peak dissociated into a major band corresponding to molecular mass of 32 kDa with minor bands at 18 and 13 kDa. 3. Polyclonal antibodies raised against the purified enzyme immunoprecipitated beta-galactosidase activity specifically from dog liver extracts and recognized a single 32 kDa band in Western blot analysis of dog tissue homogenates. This antibody did not crossreact with any protein band in tissue homogenates from other species examined except cat. 4. Western blot analysis of tissue extracts from dogs affected with GM1-gangliosidosis showed the presence of a 32 kDa band similar to that of controls.

Animals↗
PubMed1993

Flow-function dissociation following an acute dose of cocaine: effect of captopril on coronary flow.

BACKGROUND: Acute administration of cocaine leads to left ventricular dysfunction and a decrease in coronary blood flow. This experiment studied the relationship between function and flow over time in cocaine heart disease and examined the effects of captopril on this relationship. METHODS: Dogs anesthetized with pentobarbital (n = 13) were given a 3 mg/kg body weight intravenous bolus of cocaine followed by a 7 mg/kg infusion over 10 minutes. Animals were then randomly assigned to receive either captopril (0.5 mg/kg infused over 5 minutes, followed by 0.5 mg/kg/h) or an equivalent volume of saline beginning 15 minutes after cocaine administration. Coronary blood flow (radioactive microspheres and Doppler flow probes) and left ventricular function (two-dimensional echocardiogram and dP/dt) were monitored for 2 hours. RESULTS: Within 15 minutes, cocaine caused a drop in dP/dt by 39% to 42% and in coronary blood flow by 35%. Cocaine also caused an increase in left ventricular end-diastolic pressures in both groups. Cocaine resulted in prolongation of an index of end-diastolic isovolumic relaxation time (tau) from a baseline of 34 milliseconds to 56 milliseconds at 15 minutes after cocaine administration in the control group and from a baseline of 35 milliseconds to 49 milliseconds in the captopril group (P < 0.05). By 2 hours after therapy, the tau in the control group remained elevated, whereas in the captopril group it returned toward baseline. At 2 hours of observation, systolic function recovered while coronary flow remained depressed. There was no difference between the captopril and control groups in coronary blood flow or systolic cardiac function at any time during the study. CONCLUSIONS: Cocaine caused left ventricular systolic and diastolic dysfunction as well as reduced coronary blood flow. At 2 hours there is a dissociation of systolic function, which recovers, and of coronary blood flow, which does not. Captopril had no effect on coronary blood flow or systolic left ventricular function following cocaine administration.

Animals↗
PubMed1993

The results of efforts to improve compliance with supportive periodontal treatment in a private practice.

Patients who receive routine supportive periodontal treatment (SPT) tend to keep their teeth longer and enjoy greater periodontal health than those individual who do not receive this therapy. Previous studies have found less than optimal compliance to suggested SPT. The study reported in this paper covered 5 years of patient data and measured the effects of efforts to improve compliance in a private periodontal practice. These efforts included attempts at simplifying compliance, maintaining records of compliance, informing patients of the consequences of noncompliance, and attempting to identify noncompliers before active periodontal therapy was initiated. The results were measured against a similar group studied in previous work within the same office published in 1984. The main finding of the present study was an increase in complete compliance from 16% in 1984 to 32% in 1991. This increase came largely at the expense of the noncompliant group. The reason for the increase in compliance is likely due to efforts to increase compliance carried out in the office. However, other factors such as change in the hygiene practice law, increased public awareness of dental needs, and economic depression may also have affected compliance. This information suggests that noncompliance can be reduced if the problem is recognized and efforts are made to increase compliance.

Adolescent↗
PubMed1992

General slowing in semantic priming and word recognition.

Analyses of lexical decision studies revealed that (a) older (O) adults' mean semantic priming effect was 1.44 times that of younger (Y) adults, (b) regression lines describing the relations between older and younger adults' latencies in related (O = 1.54 Y-112 and unrelated conditions (O = 1.50 Y-93) were not significantly different, and (c) that there was a proportional relation between older and younger adults' priming effects (O = 1.48 Y-2). Analyses of word-naming studies yielded similar results. Analyses of delayed pronunciation data (Balota & Duchek, 1988) revealed that word recognition was 1.47 times slower in older adults, whereas older adults' output processes were only 1.26 times slower. Overall, analyses of whole latencies and durations of component processes provide converging evidence for a general slowing factor of approximately 1.5 for lexical information processing.

Adult↗
PubMed1992

The effects of acute and chronic cocaine use on the heart.

It is clear that cocaine has cardiotoxic effects. Acute doses of cocaine suppress myocardial contractility, reduce coronary caliber and coronary blood flow, induce electrical abnormalities in the heart, and in conscious preparations increase heart rate and blood pressure. These effects will decrease myocardial oxygen supply and may increase demand (if heart rate and blood pressure rise). Thus, myocardial ischemia and/or infarction may occur, the latter leading to large areas of confluent necrosis. Increased platelet aggregability may contribute to ischemia and/or infarction. Young patients who present with acute myocardial infarction, especially without other risk factors, should be questioned regarding use of cocaine. As recently pointed out by Cregler, cocaine is a new and sometimes unrecognized risk factor for heart disease. Acute depression of LV function by cocaine may lead to the presence of a transient cardiomyopathic presentation. Chronic cocaine use can lead to the above problems as well as to acceleration of atherosclerosis. Direct toxic effects on the myocardium have been suggested, including scattered foci of myocyte necrosis (and in some but not all studies, contraction band necrosis), myocarditis, and foci of myocyte fibrosis. These abnormalities may lead to cases of cardiomyopathy. Left ventricular hypertrophy associated with chronic cocaine recently has been described. Arrhythmias and sudden death may be observed in acute or chronic use of cocaine. Miscellaneous cardiovascular abnormalities include ruptured aorta and endocarditis. Most of the cardiac toxicity with cocaine can be traced to two basic mechanisms: one is its ability to block sodium channels, leading to a local anesthetic or membrane-stabilizing effect; the second is its ability to block reuptake of catecholamines in the presynaptic neurons in the central and peripheral nervous system, resulting in increased sympathetic output and increased catecholamines. Other potential mechanisms of cocaine cardiotoxicity include a possible direct calcium effect leading to contraction of vessels and contraction bands in myocytes, hypersensitivity, and increased platelet aggregation (which may be related to increased catecholamine). The correct therapy for cocaine cardiotoxicity is not known. Calcium blockers, alpha-blockers, nitrates, and thrombolytic therapy show some promise for acute toxicity. Beta-Blockade is controversial and may worsen coronary blood flow. In patients who develop cardiomyopathy, the usual therapy for this entity is appropriate.

Adrenergic beta-Antagonists↗
PubMed1991

How general is general slowing? Evidence from the lexical domain.

Three analyses are reported that are based on data from 19 studies using lexical tasks and a reduced version of the Hale, Myerson, and Wagstaff (1987) nonlexical data set. The results of Analysis 1 revealed that a linear function with a slope of approximately 1.5 described the relationship between the lexical decision latencies of older (65-75 years) and younger (19-29 years) adults. The results of Analysis 2, based on response latencies from 6 lexical tasks other than lexical decision, revealed a virtually identical linear relationship. In Analysis 3, it was found that performance on nonlexical tasks spanning the same range of task difficulty was described by a significantly steeper regression line with a slope of approximately 2.0. These findings suggest that although general cognitive slowing is observed in both domains, the degree of slowing is significantly greater in the nonlexical domain than in the lexical domain. In addition, these analyses demonstrate how the meta-analytic approach may be used to determine the limits to the external validity of experimental findings.

Adult↗
PubMed1991

General cognitive slowing in the nonlexical domain: an experimental validation.

Older and younger adults were tested on 4 nonlexical tasks: choice reaction time, letter classification, mental rotation, and abstract matching. A positively accelerated relation was observed between older and younger adults' latencies. Consistent with general slowing, the relation observed with the same subjects in each condition was more than 3 times as precise as in a comparable meta-analysis. Further analyses compared the ability of various models to describe the present data and also to predict the data on the basis of parameters estimated from a previous meta-analysis. Compared with linear models, the information-loss and overhead models provided more accurate accounts of general cognitive slowing in the nonlexical domain.

Adult↗
PubMed1990

The information-loss model: a mathematical theory of age-related cognitive slowing.

A model of cognitive slowing is proposed with the following assumption: Information is lost during processing, processing occurs in discrete steps with step duration inversely related to the amount of information currently available, and the effect of aging is to increase the proportion of information lost per step. This model correctly predicts a positively accelerated relation between latencies of older and younger adults and provides a unified account of the effects of task complexity, practice, speed-accuracy tradeoffs, and fluctuations in individual performance. Strong support for the thesis that cognitive slowing is global, and not localized in specific age-sensitive components, is provided by the fact that the model accurately predicts the latencies of older adults on the basis of those of younger adults, without regard to the nature of the task, across a latency range of nearly 2 orders of magnitude.

Adult↗
PubMed1990

A global developmental trend in cognitive processing speed.

Children respond more slowly than young adults on a variety of information-processing tasks. The global trend hypothesis posits that processing speed changes as a function of age, and that all component processes change at the same rate. A unique prediction of this hypothesis is that the overall response latencies of children of a particular age should be predictable from the latencies of young adults performing the same tasks--without regard to the specific componential makeup of the task. The current effort tested this prediction by examining the performance of 4 age groups (10-, 12-, 15-, and 19-year-olds) on 4 different tasks (choice reaction time, letter matching, mental rotation, and abstract matching). An analysis that simultaneously examined performance on all 4 tasks provided strong support for the global trend hypothesis. By plotting each child group's performance on all 4 tasks as a function of the young adult group's performance in the corresponding task conditions, precise linear functions were revealed: 10-year-olds were approximately 1.8 times slower than young adults on all tasks, and 12-year-olds were approximately 1.5 times slower, whereas 15-year-olds appeared to process information as fast as young adults.

Adolescent↗
PubMed1989

Does tissue-type plasminogen activator have direct beneficial effects on the myocardium independent of its ability to lyse intracoronary thrombi?

Tissue-type plasminogen activator (t-PA) is a widely used thrombolytic agent for treating acute myocardial infarction. Some previous studies suggest that t-PA benefits the heart independently of lysing coronary artery thrombi. The purpose of this study was to determine whether t-PA directly affects infarct size independently of lysing coronary thrombi, affects the no-reflow phenomenon, and exacerbates intramyocardial hemorrhage. We used a canine model of 2 hours of occlusion of the left anterior descending coronary artery followed by 4 hours of reperfusion. t-PA was administered 30 minutes after occlusion and was continued for 2 hours. Myocardial infarct size as a percentage of the risk zone was similar between saline (28 +/- 8%) and t-PA (35 +/- 9%) groups in a low-dose study and between saline (46 +/- 12%) and t-PA (44 +/- 12%) groups in a high-dose study. t-PA did not improve no-reflow. Intramyocardial hemoglobin level within the infarct was similar between saline (16 micrograms/mg) and high-dose t-PA (12 micrograms/mg) groups. The extent of hemorrhage assessed by intramyocardial hemoglobin correlated with infarct size. Histologic evaluation revealed that microscopic hemorrhage was confined to zones of contraction band necrosis. Neutrophil infiltration during early reperfusion was prominent. In conclusion, t-PA did not directly benefit the myocardium or no-reflow. Its effects in patients are likely due to its ability to lyse thrombi. t-PA did not cause infiltration of hemorrhage into noninfarcted tissue. Reperfusion accelerates the inflammatory response after myocardial infarction and results in early, intense neutrophil infiltration.

Animals↗