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Biomedical subjects

J A Mortimer

Publications and source records attributed to J A Mortimer.

At least 55 records · Page 3Linked to original sources
PubMed1989

Smooth pursuit eye movements in dementia of the Alzheimer type.

Smooth pursuit eye movements (SPEM) to a sinusoidally modulated target moving horizontally across a cathode ray tube screen were examined for 17 patients with dementia of the Alzheimer type (DAT) and for 14 age-matched control subjects. There were 3 target-motion conditions at frequencies representing varying ranges of target velocity. DAT patients differed from controls on all measures of smooth pursuit quality: their gain was reduced at high target velocities and lower target accelerations, they made more frequent directionally appropriate saccades and had more saccadic intrusions, they led the target with their eyes (phase lead) in all 3 conditions, and lag-adjusted cross-correlation coefficients, computed between digitized eye-movement and target signals, were lower among patients. The cross-correlation measure was most sensitive to between-group variability. These results suggest that the impaired SPEM observed in DAT patients reflect degeneration of cortical oculomotor centers, either through inappropriate saccadic intrusions in smooth pursuit as a result of physiologic disinhibition or through effects on attentional processes or both.

Acceleration↗
PubMed1989

The use of neuroendocrine immunoperoxidase markers to predict chemotherapy response in patients with non-small-cell lung cancer.

Small-cell lung cancer (SCLC), a chemotherapy-responsive disease, is characterized by neuroendocrine properties. In contrast, non-small-cell lung cancer (NSCLC) is at best moderately responsive to chemotherapy, and only 10% to 20% of cases demonstrate neuroendocrine properties. The present study is a retrospective analysis of the use of immunoperoxidase markers for neuron-specific enolase (NSE), Leu-7, and chromogranin A in NSCLC patients treated with chemotherapy. It was designed to determine if the presence of neuroendocrine markers predict for response to chemotherapy. The diagnostic slides and blocks were obtained on 52 NSCLC patients who were treated with chemotherapy (26 responders and 26 nonresponders). Immunoperoxidase studies were performed, and slides were scored without knowledge of the patient's response. Markers were positive in responders and nonresponders, respectively, as follows: NSE, 14 of 26 (54%) versus seven of 26 (27%), P = .04; Leu-7, 11 of 25 (44%) versus five of 26 (19%), P = .08; and chromogranin A, three of 26 (12%) versus 0 of 26 (0%), P = .71. Two markers were positive in 10 of 26 responders (38%) and 0 of 26 nonresponders (0%), P less than .01. Responders with two or more positive markers showed superior survival (median, 79 weeks) compared with responders with fewer than two positive markers (median, 51 weeks) and nonresponders (median, 27 weeks). These data suggest that the presence of neuroendocrine markers in NSCLC is associated with an increased likelihood of response to chemotherapy and may add to the standard parameters (performance status, weight loss) used to select patients for chemotherapy.

Adult↗
PubMed1988

Latency and accuracy of word recognition in dementia of the Alzheimer type.

The sensitivity of reaction time (RT) measurement in assessing cognitive decline in dementia of the Alzheimer type (DAT) was evaluated. Sixteen DAT patients and 16 normal elderly controls, matched for age and education, read 50 stimulus words presented individually on a cathode-ray tube. DAT patients exhibited a significantly greater cognitive impairment as shown by multivariate analysis of variance (p less than 0.0001). Canonical variate correlations revealed RT (0.961) to be more sensitive to decline in cognitive functioning in dementia than the measure of number of reading errors (0.559). Results confirm that RT is a highly sensitive measure of central nervous system integrity, which allows for a more refined investigation of a patient's cognitive deficit than is obtainable with traditional test measures. These findings suggest that chronometric measures should be incorporated in clinical and research studies attempting to document the existence and severity of cognitive impairment in neurodegenerative disease.

Aged↗
PubMed1988

The dementia of Parkinson's disease.

An understanding of the causes, nature, and course of intellectual impairment in Parkinson's disease (PD) is essential for the correct development of therapy. This article reviews the causes of the dementia of PD, its primary clinical and pathological features, and its course.

Aged↗
PubMed1987

Premovement silence in agonist muscles preceding maximum efforts.

Electromyographic silent periods (premovement silence) preceding the initial agonist burst were studied in 11 healthy subjects who performed rapid forearm flexions and extensions. Premovement silence occurred with higher frequency during self-paced movements when subjects produced maximum power efforts than during a reaction time paradigm. The occurrence and duration were significantly correlated with the peak acceleration of the movement. Premovement silence occurred specifically in those muscles involved in the intended movement, often in several synergists with different latencies and durations. The shortest latency of premovement silence was considerably briefer than that of the earliest voluntary increase in EMG. The findings suggest that premovement silence may increase peak muscular force by bringing motoneurons into a nonrefractory state prior to their activation. The fact that it occurred on some, but not all, trials within single subjects and had a variable duration from trial to trial suggests that it may be a learned, rather than automatic, motor response.

Action Potentials↗
PubMed1987

Subtypes of Parkinson's disease defined by intellectual impairment.

Sixty patients with Parkinson's disease were administered a battery of neuropsychological tests. Using regression data from a matched normal control sample, age- and education-residualized test scores were obtained for the patients. Three clusters of patients were identified: those with both verbal memory and visuospatial reasoning disorders (n = 24), those with memory impairment only (n = 17) and those with normal intellectual function (n = 12). Analysis of variance and planned comparisons (Newman-Keuls) were performed to detect group differences. No difference on 9 memory measures were found between the 2 memory-impaired groups. However, these groups differed significantly on all memory measures from the group with normal function. The 2 memory-impaired groups also differed significantly from each other on all 7 measures of visuospatial reasoning. The group with memory loss only was significantly younger than the group with both visuospatial and memory impairment and also demonstrated less bradykinesia. Otherwise, there were no group differences in the severity of motor signs, disease duration or duration of levodopa therapy. These findings support a different etiology for motor and intellectual deficits in Parkinson's disease.

Age Factors↗
PubMed1986

Pathologic correlates of dementia in Parkinson's disease.

Histopathologic studies of the cerebral cortex, hippocampus, and three subcortical nuclei were performed in four patients with Parkinson's disease whose mental status had been evaluated by neuropsychologic testing. Clinicopathologic correlations suggest that dementia with marked visuospatial disturbance as well as severe aphasia may be associated with severe neuronal loss in subcortical nuclei, without significant numbers of plaques or tangles in the hippocampus and cerebral cortex. Furthermore, memory loss may not be consistently related to neuronal loss in the nucleus basalis of Meynert, particularly in non-Lewy body parkinsonism.

Aged↗
PubMed1986

Exercise therapy for Parkinson's disease.

The outcomes of two different 12-week exercise programs were assessed by machine measurements of motor signs, tests of grip strength, motor coordination and speed, and neurophysiologic determinations of long-latency stretch responses in two groups of Parkinson patients matched for age, sex and stage of disease. The programs tested included an exercise program developed by the United Parkinson Foundation and a program of upper body karate training. Outcomes of these programs were similar. The majority of patients in both groups showed improvements in gait, tremor, grip strength and motor coordination on tasks requiring fine control. In one task involving whole body coordination there was a decline in function, while muscle rigidity was unchanged. The findings suggest that exercise is a useful adjunct to pharmacologic therapy.

Exercise Therapy↗
PubMed1985

A case-control study of dementia of the Alzheimer type.

A case-control study to assess factors of possible etiologic significance to dementia of the Alzheimer type was conducted with 78 male cases diagnosed in 1979-1982 at the Veterans Administration Medical Center in Minneapolis, Minnesota and age-race-sex-matched hospital and neighborhood controls (14 of 16 autopsied cases were histopathologically confirmed). Information was obtained on variables relevant to vital, genetic, and immunologic hypotheses, and on possible occupational and environmental exposures, drug use, psychologic stress, smoking, and alcohol consumption. The only major difference between patients with dementia of the Alzheimer type and controls was a significantly greater occurrence of antecedent head trauma in the patients (odds ratio = 4.50). This finding is consistent with the literature on posttraumatic dementia but its importance is presently unclear.

Adult↗
PubMed1985

Head injury as a risk factor for Alzheimer's disease.

A case-control study was performed in which the frequency of prior head injury was assessed in 78 patients with dementia of the Alzheimer type (DAT) and 124 control subjects matched for age, sex, and race. A history of head injury with loss of consciousness was reported in 25.6% of patients and 5.3% and 14.6% of hospital and neighborhood controls, respectively. Matched-pair analysis of patients and hospital controls yielded an odds ratio of 4.50, which was significant (p less than 0.01). The ranges of times of occurrence of head injuries were similar in patients and controls, spanning several decades. The findings suggest a possible etiologic role for head injury in DAT.

Aged↗
PubMed1982

Dementia in Parkinson disease: a neuropsychological analysis.

An extensive set of neuropsychological measures was administered to 60 Parkinson's disease patients and age-, sex-, and education-matched controls in order to investigate the nature and prevalence of the cognitive deficit in the disease. Parkinsonian patients performed significantly poorer on all measures with the exception of tests for apraxia and object recognition, and on a test of vocabulary knowledge. Discriminant analysis of the test data revealed that over 93% of patients are impaired relative to matched controls, but that assigning a prevalence rate for dementia in the disease may be difficult due to the continuous distribution of cognitive deficits.

Cognition↗