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Biomedical subjects

R E Dustman

Publications and source records attributed to R E Dustman.

At least 55 records · Page 3Linked to original sources
PubMed1979

Cortical evoked responses and response decrement in nonretarded and Down's syndrome individuals.

Cortical evoked responses were recorded from 66 nonretarded and 66 Down's syndrome subjects. Analyses of single-trial responses from which evoked responses were averaged indicated that visual evoked response amplitude in nonretarded subjects was more dependent on variability than on amplitude of single responses. Response decrement, the tendency for evoked responses to attenuate with repetitive stimulation, was clearly observed in the evoked responses of the nonretarded subjects but was minimal in those of the Down's syndrome group. The findings support the concept that the development of inhibitory processes in Down's syndrome persons' brains may be halted or delayed at an early age.

Acoustic Stimulation↗
PubMed1978

Sustained ingestion of methadone and the sleep of monkeys.

Methadone HCl was administered daily to four stump-tailed macaques. The animals' sleep was periodically examined throughtout a year of methadone maintenance and, in two animals, during eight months of withdrawal. REM sleep was substantially decreased by methadone treatment and gradually returned to predrug values over a 6- to 8-month period of maintenance. Measures of non-REM sleep and awakenings showed similar disruption with no return to predrug values. These changes were not correlated with alterations in plasma-methadone concentrations. REM sleep rebound occurred temporarily upon drug withdrawal in two animals, but no consistent sleep disruption was apparent during the subsequent eight months. Contrary to some suggestions, therefore, tolerance to the sleep-disruptive effects of the drug may be specific and incomplete, and extended REM rebound upon withdrawal is not a universal response.

Animals↗
PubMed1978

Visual and somatosensory evoked potentials characteristics of patients undergoing hemodialysis and kidney transplantation.

The effects of prolonged hemodialysis and kidney transplantation on visual and somatosensory evoked potentials and EEG frequency were assessed. Significant changes were found in both amplitude and latency characteristics of evoked potentials recorded from eight hemodialysis patients. Their evoked potentials tended to be of longer latency and larger amplitude when compared to responses of an age-matched control group. This was true for visual and somatosensory responses recorded from several scalp locations. A correlational analysis revealed no consistent relationship between blood chemistries and evoked potential characteristics. EEG power spectral analysis showed that the dominant frequency of five of the eight dialysis patients was in the 8-10 c/sec range. Two other patients demonstrated EEG frequencies which were scattered across the 3-12 c/sec range while for another subject the dominant frequency was 7-8 c/sec. The evoked potential latencies and amplitudes of patients with successful kidney transplant tended to return to the normal range and their predominant EEG frequency increased to around 10 c/sec. A depression of function in those neural systems underlying the visual and somatosensory modalities, along with a reduction in the cortical suppression of afferent stimulation normally exerted by the thalamic reticular system and the basal ganglia were postulated to account for the reported findings.

Adult↗
PubMed1978

Sawtooth waves: concomitants of rapid eye movement sleep in monkeys.

Sawtooth waves, 2--3 c/sec activity of at least 40 micro V, occurred primarily during clusters of REMs in stump-tailed macaques. On the average the activity began well after the onset of REMs but occasionally occurred soon before or immediately after a cluster of REMs. The activity was clearly defined but occupied less than 0.6% of an 8-h sleep record. A sawtooth burst was, on the average, 7.5 sec in duration.

Animals↗
PubMed1978

Differential effects of convulsants on visually evoked responses in the albino rat.

Visually evoked responses (VERs) were recorded from primary visual cortex in unanesthetized albino rats during pharmacological modulation by one of the following convulsant agents: Physostigmine, picrotoxin, strychnine and Metrazol. The data were analyzed in terms of effects on VER components. The rat VER consists of six distinct waves constituted by three positive peaks (P1--P3) and three negative peaks (N1--N3). Results indicate a differential convulsant action on VER components. The administration of picrotoxin, resulted in a suppression of the peak amplitude of P1--N1 and delayed peak latencies of all components. Strychnine reliably shortened P1, N1 and P2 peak latencies, significantly increased N3 peak latency and only suppressed P3--N3 amplitude. Physostigmine essentially suppressed all component amplitudes but only increased peak latencies for P2 and P3 components. Metrazol, in general, was found to be relatively ineffective in the alteration of any VER component in a systematic manner. The data are discussed in terms of differential modes of convulsant action on the visual system. The results are likewise discussed with respect to their implications for convulsant modulation of photically evoked after-discharges.

Animals↗
PubMed1978

Life span changes in the averaged evoked responses of Down's syndrome and nonretarded persons.

Visual, auditory, and somatosensory evoked responses were recorded from six age groups of Down's syndrome persons and age and sex-matched nonretarded individuals ranging in age from 5 to 62 years and assigned to groups on the basis of observable signs of development and aging. Results indicated that, regardless of stimulus modality, the amplitude of late wave components was dramatically larger for Down's syndrome than for the nonretarded subjects. Where obvious amplitude reduction occurred with maturation and aging among nonretarded subjects, amplitude changes were generally absent among Down's syndrome subjects. The findings for Down's syndrome persons were discussed in terms of deficits in central inhibition and abnormalities in neuronal excitability to different levels of stimulus intensity.

Adolescent↗
PubMed1977

WAIS performance in young normal, young alcoholic, and elderly normal groups: an evaluation of organicity and mental aging indices.

Investigated the effects of alcoholism and advanced age on Wechsler Adult Intelligence Scale (WAIS) performance and tested the validity of indices of "organicity" and "mental aging" derived from WAIS scores. The WAIS was administered to three groups of 20 males each: young normal (mean age 31 years), young alcoholic (mean age 33 years), and elderly normal (mean age 71 years. In terms of scaled scores, the young normal group was generally superior to the other groups on Verbal and Performance subtests, and the alcoholic and elderly groups resembled each other more on the Verbal than the Performance subtests. In view of an almost 40-year difference in age between the young alcoholic and the elderly normal Ss, similarities in pattern of performance provided some evidence for the hypothesis of "premature aging" in alcholics.

Adult↗
PubMed1977

Sudden toxicity of methadone in monkeys: behavioral and electrophysiological evidence.

A sudden and potentially lethal toxic reaction to a previously well-tolerated maintenance dose of methadone occurred in 4 of 6 monkeys. The reaction was characterized by gross behavioral and respiratory depression and a marked attenuation of both early and late components of the visual evoked response with an increase in most latencies. The nature of the evoked response alteration suggests a widespread central nervous system depressant effect of the drug during toxicity. Concomitant with the toxic reactions were dramatic increases in plasma methadone concentrations. Therefore the observed changes in sensitivity to methadone would appear to be the consequence of a sudden shift in pharmacokinetics resulting in toxic plasma concentrations.

Animals↗
PubMed1977

Visual evoked response and behavioral correlates of plasma methadone concentrations in cats.

Twelve cats were implanted with cortical and depth electrodes. After they recovered from the operation, visual evoked responses (VERs) were recorded at 20 min following saline and methadone (0.5, 1, 2, 3, 4 mg/kg) administered IP in a semi-random order to each cat. Four other cats were similarly drugged and plasma was obtained for radioimmunoassay of methadone content. At the three lowest dose levels behavioral excitation and salivation were evident in some cats, while their VER configuration remained essentially unaltered and plasma methadone was barely measurable. Following the 3 and 4 mg/kg doses plasma methadone concentration increased dramatically, behavioral excitation and salivation were evident in most cats and VERs were reliably altered. The VER alterations, consisting of amplitude attenuation and a decrease in some latencies, were restricted to secondary VER components occurring between 50 and 100 msec despite the animals' extreme behavioral excitation. These results suggest that the reticular formation is not a principal site of the drug's effect.

Animals↗
PubMed1977

Neuropsychological correlates of chronic alcoholism and aging.

Independent investigations of alcoholism and aging have demonstrated significant parallels between the two phenomena suggesting the possibility of "premature aging" as a result of alcoholism. To test this hypothesis a cross-sectional design was utilized with three groups of 20 male subjects: young normal (mean age 31 years), young alcoholics (mean age 33 years), and elderly normal (mean age 71 years). Eleven objective measures, selected from a battery of sensory and perceptual motor tests routinely used to evaluate cerebral dysfunction in hospitalized patients, were compared for the three groups. The results indicated a definite general decline in neuropsychological functioning with aging and suggested a similar trend with alcoholism. The tendency seen with alcoholism was least apparent with regard to fundamental sensory-motor functions and the perceptual functions of vision and audition and most apparent with regard to short term memory and abstract reasoning, i.e., higher mental processes. The results provided support for the hypothesis that chronic alcoholism causes premature aging of neuropsychological functions and possibly the brain.

Adult↗
PubMed1976

Sensory, perceptual, motor and cognitive functioning and subjective reports following oral administration of delta9-tetrahydrocannabinol.

Three dose levels, 0.2, 0.4, and 0.6 mg/kg, of delta9-tetrahydrocannabinol (THC) and a placebo were orally administered to 10 frequent and 10 occasional marijuana users. Following ingestion of each dose and the placebo, objective tests selected from a battery of sensory and perceptual motor tests routinely used to evaluate cerebral dysfunction in hospitalized patients were administered. The influence of delta9-THC on proficiency and variability of performance was minimal. However, when individual test scores and variabilities were combined and converted to standard scores, allowing for analysis of overall performance, THC had a small but consistent detrimental effect on both proficiency and variability of performance. In contrast, THC exerted profound effects on the subjective experiences of the volunteers as assessed by the Subjective Drug Effects Questionnaire. Subjective changes in mood, feeling, perception and somatic sensations were reported by all subjects but were more pronounced in the occasional user group. It was proposed that the small impairment noted in objective test performance after ingestion of delta9-THC as contrasted to the large effects on subjective responses suggests that the principal effects of marijuana are on the autonomic nervous system rather than on higher cortical functions.

Adult↗
PubMed1976

A miniature, readily available electrode pedestal for recording cerebral and other electrophysiological activity from several species.

A miniature, commercially available electrode pedestal with prewired and prenumbered leads was designed. It possesses long-term electrical reliability and can be applied to a wide range of animal species. It can be easily modified to record electroencephalograms, evoked responses, and related physiological measurements. The device is relatively small, with keyed and lock-down parts, and is resistant to damage.

Animals↗