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Biomedical subjects

R S Wilson

Publications and source records attributed to R S Wilson.

At least 19 recordsLinked to original sources
PubMed1992

Clinical correlates of high signal lesions on magnetic resonance imaging in Alzheimer's disease.

The pathophysiology and clinical significance of high signal lesions, visualized on magnetic resonance imaging (MRI) in patients with Alzheimer's disease (AD), remain controversial. Since they are known to correlate with vascular disease and vascular risk factors, we reviewed the clinical correlates of periventricular high signal (PVH) and subcortical white matter lesions (WML) in a sample of 106 patients with probable AD, excluding persons with treated vascular risk factors or symptomatic cerebrovascular and cardiovascular disease. Grade 2 PVH were seen in 26 (25%) and scattered WML were identified in 29 (18%). PHV were associated with advancing age and gait disturbance. WML were associated with gait disturbance and incontinence. Neither radiologic finding was related to dementia severity. The findings suggest that these lesions are common in patients with AD even when those with evidence of cerebrovascular disease are excluded; their presence, therefore, should not preclude a diagnosis of AD. Additionally, the data suggest that HSL on MRI may be one of many risk factors associated with functional disability in persons with probable AD.

Aged↗
PubMed1992

Ideational fluency in Parkinson's disease.

Recent research on Parkinson's disease (PD) suggests that executive functions are impaired but that visuospatial functions may be spared. This dissociation has been attributed to dysfunction in ascending dopaminergic pathways affecting the prefrontal cortex. We investigated these ideas in a sample of intellectually intact patients with idiopathic, optimally treated PD (N = 20) and in spouse controls (N = 15); the groups were divided into young (age < 60) and old subgroups, each comparable on education, vocabulary level, and Mini-Mental State scores. Six tasks were selected from a set of factor-referenced cognitive tests to measure three abilities: (1) ideational fluency (ability to generate ideas), (2) flexibility of use (ability to shift mental set), and (3) spatial orientation (ability to perceive spatial patterns). PD patients were impaired only on the ideational fluency factor (p = .01). An age-related deficit was seen on the spatial factor (p < .05) with a trend on the flexibility factor (.05 < p < .10). No interactions were significant. The findings suggest that when age and verbal intelligence are controlled, PD patients show no deficit on purely spatial tasks; in contrast, patients seem less able to generate ideas though capable of shifting from one idea to another.

Brain Mapping↗
PubMed1992

Ondansetron does not affect alfentanil-induced ventilatory depression or sedation.

Ondansetron is a selective 5-hydroxytryptamine type 3 receptor antagonist effective as an antiemetic in patients experiencing post-operative or cancer chemotherapy-induced nausea and vomiting. Currently, no information is available regarding the interaction of ondansetron with opioids, although a serotonin antagonist might be expected to modify some opioid actions. This study was designed to measure the effects of ondansetron on alfentanil-induced ventilatory depression and sedation in healthy male volunteers. Ventilatory drive (measured as the end-tidal CO2 necessary to produce a minute ventilation of 15 l/min) was determined in 29 subjects using a modification of the Read rebreathing technique. Sedation was measured by asking the subjects to complete visual analog scales. Alfentanil was administered as a bolus (5 micrograms/kg) followed by a continuous infusion (0.25-0.75 micrograms.kg-1.min-1) for at least 90 min. Study medication (ondansetron 8 or 16 mg or vehicle placebo) was then administered in a randomized, double-blind manner, and the alfentanil was infused for an additional 15 min. Measurements of ventilatory drive and sedation were made at baseline, during alfentanil infusion, after study medication, and at 30-min intervals after alfentanil was discontinued. Alfentanil produced significant ventilatory depression (P less than 0.001) and sedation (P less than 0.001) in all three groups. Neither placebo nor ondansetron produced further change in the intensity of either alfentanil effect. After discontinuation of the opioid, both ventilatory depression and sedation decreased, and the rate of recovery was not significantly different between groups. The data indicate that alfentanil-induced sedation and ventilatory depression are not significantly affected by the subsequent administration of ondansetron.

Alfentanil↗
PubMed1991

Episodic and semantic memory in early versus late onset Alzheimer's disease.

The aim of this study was to replicate and extend previous work demonstrating selective impairment of semantic, but not episodic, memory in late versus early onset Alzheimer's disease (AD). Measures of episodic and semantic memory were administered to 12 pairs of patients; early (less than or equal to 62) and late (greater than or equal to 68) onset pairs were matched on dementia severity and education. As hypothesized, the groups did not differ on the three episodic memory measures but did on two of three semantic memory measures. In conjunction with prior research, these findings indicate that late onset AD is characterized by more profound impairment on measures of semantic processing.

Age Factors↗
PubMed1991

Nuisance parameters in the assessment of noncognitive manifestations of dementia.

Measures of noncognitive disturbances in dementia typically rely on ratings by informants. In this study, method variance in measures of affect, behavior, and functional competence was evaluated by comparing ratings from 2 types of informants (spouse vs. child) in patients with probable Alzheimer's disease. No differences were observed on 5 variables; for 2 measures of behavior disturbance and 1 measure of functional disability, ratings obtained from child informants were significantly higher than spouse ratings for patients at comparable levels of dementia severity. Although the effect of the rater dimension was relatively small and selective, the findings suggest the need for further research on potential sources of bias in the ratings of noncognitive features of the dementia syndrome.

Activities of Daily Living↗
PubMed1991

Predictors of behavioral disturbance in Alzheimer's disease.

The relationship of behavioral disturbances in Alzheimer's disease to disease severity, age at onset, and the presence of extrapyramidal signs was investigated in three studies. Five categories of behavior disturbance were ascertained through structured interview with the patient's primary caregiver: apathy, agitation, psychotic symptoms, disinhibition, and irritability. In Study 1, measures of disease severity accounted for 42% of the variance in the Apathy scale but less than 20% of the variance in the remaining scales. In Study 2, the presence of extrapyramidal signs was associated with increased Apathy and moderated the association between disease severity and the Psychotic Symptoms and Irritability scales. In Study 3, age at onset was associated with the Agitation scale and moderated the association between disease severity and the Apathy, Psychotic Symptoms, and Irritability scales. The findings are discussed in terms of the clinical heterogeneity within Alzheimer's disease, the possible biological bases of these behavioral disturbances, and the psychometric issues pertinent to their measurement.

Age Factors↗
PubMed1991

Hallucinations and associated factors in Alzheimer's disease.

In a consecutive sample of 230 community-dwelling patients with probable Alzheimer's disease, a structured interview yielded evidence of current hallucinations in 29.1% and misperceptions in another 11.3%. Visual and auditory modalities were similarly represented in apparent hallucinations. Hallucinations prior to the current monitoring period were rare among patients with misperceptions or with no perceptual abnormality. The probability of hallucinations was associated with the severity of cognitive dysfunction, the degree of other behavioral disturbances, and the presence of extrapyramidal signs. A logistic regression model predicting hallucinations based on these diverse clinical features accurately classified 87.0% of the sample.

Activities of Daily Living↗
PubMed1979

Analysis of longitudinal twin data. Basic model and applications to physical growth measures.

A formal model is presented for the analysis of longitudinal twin data, based on the underlying analysis-of-variance model for repeated measures. The model is developed in terms of the expected values for the variance components representing twin concordance, and the derivation is provided for computing within-pair (intraclass) correlations, and for estimating the percent of variance explained by each component. The procedures are illustrated with physical growth data extending from birth to six years, and concordance estimates are obtained for average size and for the pattern of spurts and lags in growth. A test of significance is also described for comparing monozygotic twins with dizygotic twins. The procedures are particularly useful for assessing chronogenetic influences on development, especially whether the episodes of acceleration and lag occur in parallel for genetically matched twins. The model may be employed with psychological data also.

Analysis of Variance↗
PubMed1979

Some 11-substituted tetrahydrocannabinols. Synthesis and comparison with the potent cannabinoid metabolites 11-hydroxytetrahydrocannabinols.

A series of compounds was prepared in which the 11-hydroxyl of 11-hydroxy-delta8-THC, the potent metabolite of delta8-THC, was replaced by a methyl, methyoxy, amino, or acetamido group. All of the compounds tested produced behavioral changes in dogs, but only the methoxy compound has analgesic properties in mice. An isosteric oxime was inactive in mice.

Analgesics↗
PubMed1979

Some 9-hydroxycannabinoid-like compounds. Synthesis and evaluation of analgesic and behavioral properties.

A series of 9-hydroxylated cannabinoid-like compounds was prepared and tested for analgesic properties in mice and behavioral properties in dogs. Although the prototype compound, 9-nor-9-hydroxyhexahydrocannabinol, has potent antinociceptive activity in laboratory animals, the new analogues were relatively inactive. All of the compounds produced an alteration of behavior in unanesthetized dogs. Two of the compounds produced cannabinoid-like effects and the other two produced general CNS depression.

Analgesics↗
PubMed1979

Extrapulmonary factors influencing the ratio of arterial oxygen tension to inspired oxygen concentration in burn patients.

The ratio of arterial oxygen tension to inspired oxygen concentration (PaO2/FIO2) as an index of respiratory function was evaluated in 22 patients with body surface area burns of 15--80%. These results indicate that this ratio is limited in its applicability because extrapulmonary factors, such as cardiac output, oxygen consumption, and arterial oxygen content, can affect this index by alterations in the amount of venous desaturation. Useful estimates of intrapulmonary right to left shunt (Qs/Qt) from PaO2/FIO2 were obtained only when arteriovenous oxygen content differences (avDO2) were between 3--5 ml/dl. There were avDO2 values above and below 3--5 ml/dl in at least 35% of the observations. Under these circumstances, PaO2/FIO2 did not correctly reflect changes in Qs/Qt. Blood gases from central venous catheters did not mirror changes in true mixed venous blood and, thus, can lead to erroneous estimations of Qs/Qt. Rational therapy of reduced arterial oxygen saturation requires measurement of both extra- and intrapulmonary factors contributing to arterial desaturation. Measurement of PaO2/FIO2 alone will not estimate these factors.

Adolescent↗
PubMed1979

Hydatid disease presenting as tension pneumothorax.

The case of stockfarmer with hydatid disease which presented as a left tension pneumothorax is described. The diagnosis was not made until the patient underwent a thoracotomy for a complicating empyema.

Adult↗
PubMed1978

Synchronies in mental development: an epigenetic perspective.

Early mental development is analyzed from an evolutionary viewpoint and related to the dynamic interplay of genetic programming, maturational status, and environmental influence. Data are reported from a large sample of twins and siblings who have been tested longitudinally from 3 months to 6 years of age. Monozygotic twins became increasingly concordant with age and also paralleled each other for the spurts and lags in development. Dizygotic twins became less concordant with age and eventually matched their singleton siblings as closely as one another. The overall results suggested that the course of mental development is guided by the intrinsic scheduling of the genetic program acting in concert with maturational status and environmental influence.

Behavior↗