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Biomedical subjects

S Hale

Publications and source records attributed to S Hale.

At least 19 recordsLinked to original sources
PubMed2000

Behavioral evidence for brain-based ability factors in visuospatial information processing.

The present study examined possible parallels between the structure of human visuospatial abilities and the organization of the neural systems. Forty-eight participants were tested on seven speeded visuospatial tasks. Three of these tasks were constructed so as to rely primarily on known ventral stream functions and four were constructed so as to rely primarily on known dorsal stream functions. Both sets of tasks spanned approximately the same range of difficulty as indexed by both the speed and accuracy of decision making. Factor analysis of response times on the seven tasks revealed only two significant factors. The putative ventral stream tasks all loaded heavily on one factor (mean loading=0.843) but only weakly on the other factor (mean loading=0.222); the putative dorsal stream tasks showed the opposite pattern in that they all loaded heavily on the second factor (mean loading=0.828) but only weakly on the first factor (mean loading=0.229). These findings are consistent with the hypothesis that human visuospatial abilities can be classified using categories based on the specializations of underlying neural structures and systems.

Adult↗
PubMed1999

Selective interference with verbal and spatial working memory in young and older adults.

Young and older adults were administered digit and location memory span tasks with and without verbal and spatial secondary tasks. Age differences were greater in location span than in digit span; however, there were no age differences in either the magnitude or pattern of effects of secondary tasks. There were also no age differences in the effects of secondary tasks on a combined (digit and location) task. On the digit and location span tasks, both young and older adults showed only domain-specific interference: naming colors selectively interfered with memory for digits, leaving memory for locations unaffected; pointing to matching colors selectively interfered with memory for locations, leaving memory for digits unimpaired. The results of the present study suggest a greater age deficit in spatial working memory than in verbal working memory, but provide no evidence of an age deficit in susceptibility to interference by secondary tasks in either domain.

Adolescent↗
PubMed1998

Cerebellar contribution to linguistic processing efficiency revealed by focal damage.

The cerebellum's role in cognitive skills was examined in a child (L.C.) with focal injury to the left cerebellum. Initial symptoms included aphasia and dysarthria. At 3 and 9 months post-injury, clinical neuropsychological tests revealed persistent psychomotor slowing as well as deficits in executive functions. Further cognitive testing at 13 and 16 months post-injury demonstrated that L.C. processed information from both the linguistic and nonlinguistic domains more slowly than age-, grade- and sex-matched controls. Notably, her linguistic processing was more than twice as slow as that of her peers, whereas her nonlinguistic processing was only approximately 20% slower. Within each domain the degree of cognitive slowing was approximately the same across diverse tasks. These results are consistent with the hypothesis of a cerebellar contribution to cognitive processing, particularly the processing of linguistic information.

Cerebellar Diseases↗
PubMed1998

Short-term and long-term memory in early temporal lobe dysfunction.

Following medial temporal damage, mature humans are impaired in retaining new information over long delays but not short delays. The question of whether a similar dissociation occurs in children was addressed by testing children (ages 7-16) with unilateral temporal lobe epilepsy (TLE) and controls on short- and long-term memory tasks, including a spatial delayed response task (SDR). Early-onset TLE did not affect performance on short delays on SDR, but it did impair performance at the longest delay (60 s), similar to adults with unilateral medial temporal damage. In addition, early-onset TLE affected performance on pattern recall, spatial span, and verbal span with rehearsal interference. No differences were found on story recall or on a response inhibition task.

Age of Onset↗
PubMed1997

General lexical slowing and the semantic priming effect: the roles of age and ability.

Older adults performed three lexical information-processing tasks approximately 1.3 times slower than young adults. Consistent with general lexical slowing, slopes of regressions based on individual subjects' RTs on two of the tasks (single lexical decision and category judgment) did not differ from slopes based on the third (double lexical decision) task. Moreover, slopes based on the single lexical decision and category judgment tasks accurately predicted the size of semantic priming effects on the third (double lexical decision) task. This was true for the older group as a whole, and also for subgroups of fast, medium and slow older adults, as well as for young adult subgroups. The size of the semantic priming effects for the fast old and slow young subgroups (who differed in age but not in processing speed) were approximately equal, consistent with the idea that the effect of age on priming is entirely attributable to slowing. Across all tasks, each old subgroup (fast, medium, or slow) showed the same degree of slowing relative to the corresponding young subgroup, so that the differences in RTs observed between subgroups in the young sample were magnified in the old sample. Taken together, the present findings suggest that ability-related differences in lexical processing speed may be functionally equivalent to age-related differences and that both factors interact to determine performance on speeded lexical tasks.

Adult↗
PubMed1997

Verbal and spatial working memory in school-age children: developmental differences in susceptibility to interference.

The development of verbal and spatial working memory was investigated with an interference paradigm. Memory spans were obtained from 3 groups (8-, 10-, and 19-year-olds) under 6 different conditions: Two primary memory tasks (1 verbal, 1 spatial) were administered in isolation and in conjunction with 2 versions of a secondary task. The primary tasks required recalling a series of visually presented digits and recalling the locations of Xs in a series of visually presented grids. The secondary tasks required reporting the color of the stimuli as they were presented using either a verbal or a spatial response. Analyses revealed that all age groups showed domain-specific interference (i.e., interference by a secondary task from the same domain as the primary task), but only the 8-year-olds also showed nonspecific interference (i.e., interference by a secondary task from a domain different than the primary memory task), suggesting that at least some executive functions do not reach adult levels of efficiency until approximately age 10.

Adolescent↗
PubMed1995

A novel biologic function of serum amyloid A. Induction of T lymphocyte migration and adhesion.

In the course of an inflammatory response, the concentration of serum amyloid A (SAA), a hepatocyte-derived acute phase protein, increases up to 1000-fold above the normal level. Although SAA was previously thought to be immunosuppressive, we recently reported that SAA is a potent chemoattractant for monocytes and neutrophils. The present study shows that recombinant human (rh) SAA also induces directional migration of T cells in vitro. Phenotypic analyses revealed that CD4+ and CD8+ T cell subsets were equally responsive to rhSAA, whereas CD45RA cells were also not selectively attracted by rhSAA. The T cell chemotaxis induced by rhSAA was inhibited by pretreatment of cells with pertussis toxin, suggesting the interaction of rhSAA with a G-protein-coupled receptor species. T cells pretreated with an optimal concentration of SAA exhibited enhanced adherence to human umbilical cord endothelial cell monolayers. Subcutaneous administration of rhSAA into huPBL-SCID mice caused the infiltration of human T lymphocytes at the injection sites by 4 h. These results suggest that SAA may play an important role in recruiting T lymphocytes, as well as neutrophils and monocytes into inflammatory lesions.

Animals↗
PubMed1995

Preconditioning stimuli and inadvertent preconditioning.

There are several factors besides brief episodes of total coronary occlusion which can provide sufficient stress to result in a preconditioning-like effect on the size of a myocardial infarction. Partial coronary artery stenosis, hypoxia, stretch, catecholamines, rapid pacing, and certain pharmacologic therapies may provide preconditioning stimuli. These same factors as well as mechanical complications in which a coronary artery is briefly occluded or stenosed prior to a subsequent coronary occlusion may lead to inadvertent preconditioning and confound the results of experimental cardiology studies.

Coronary Disease↗
PubMed1995

Working memory following improvements in articulation rate in children with cerebral palsy.

It has been postulated that rehearsal rate is the primary determinant of working memory capacity for verbal material (Baddeley et al., 1975). A previous study of normal control children and children with spastic diplegic cerebral palsy (SDCP) suggested that covert rather than overt rehearsal rate determines working memory capacity (White et al., 1994). In the current study, a subset of SDCP children who received a surgical treatment to relieve spasticity were retested on measures of articulation rate and memory span. A subset of control children from the original study were also retested. The SDCP group showed improvements in articulation rate at follow-up, though memory span did not change and was again equivalent to that of controls. These findings indicate that increases in articulation rate are not necessarily accompanied by improvements in memory span, and provide additional evidence that working memory capacity may be determined by covert rather than overt articulatory rehearsal.

Articulation Disorders↗
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↗