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Biomedical subjects

D L Robinson

Publications and source records attributed to D L Robinson.

At least 91 records · Page 5Linked to original sources
PubMed1986

Hepatocellular carcinoma presenting as bone pain.

Hepatocellular carcinoma is an uncommon malignancy in the western world, and its presentation as symptomatic skeletal metastasis is rare. The following describes a patient whose initial complaint was arm pain that was subsequently found to be due to metastatic hepatocellular carcinoma. A review of the literature describing skeletal involvement by hepatocellular carcinoma is included.

Arm↗
PubMed1986

Saccade-related and visual activities in the pulvinar nuclei of the behaving rhesus monkey.

We studied three subdivisions of the pulvinar: a retinotopically organized inferior area (PI), a retinotopically mapped region of the lateral pulvinar (PL), and a separate, visually responsive component of the lateral pulvinar (Pdm). Single neurons were recorded in these regions from awake, trained rhesus monkeys, and we correlated the discharge patterns of the cells with eye movements. About 60% of the neurons discharged after saccadic eye movements in an illuminated environment and had either excitatory, inhibitory, or biphasic (inhibitory-excitatory) response patterns. These responses were most often transient in nature. Neurons with excitatory activity had a mean onset latency of 72 ms after the termination of the eye movement. Latencies for cells with inhibitory responses averaged 58 ms. In sharp contrast, the cells with biphasic response patterns became active before the termination of the eye movement. A unique set of these neurons termed saccade cells, were active with visually guided eye movements in the light, with the same eye movements made to a briefly pulsed target in the dark, and for similar eye movements made spontaneously in total darkness. The activity was present with the appropriate saccade, independent of the beginning eye position. Biphasic response patterns were typical of these saccade cells. Saccade cells were most common in Pdm and PI. About half of the saccade cells also had some visual response that was independent of eye movement. A second group of cells was active with saccadic eye movements in the light but not in the dark. Some of these cells had clear visual responses that could account for their activity following eye movements; others had no clear visual receptive field.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1985

Responses of pulvinar neurons to real and self-induced stimulus movement.

Many neurons in the pulvinar nuclei of awake monkeys respond to real image motion while the animal maintains fixation. Many of these same cells do not discharge to comparable stimulus movement when it is caused by an eye movement. This lack of sensory response is most likely mediated by an extraretinal signal.

Animals↗
PubMed1985

Pulvinar nuclei of the behaving rhesus monkey: visual responses and their modulation.

We have examined the properties of neurons in three subdivisions of the pulvinar of alert, trained rhesus monkeys 1) an inferior, retinotopically mapped area (PI), 2) a lateral, retinotopically organized region (PL), and 3) a dorsomedial visual portion of the lateral pulvinar (Pdm), which has a crude retinotopic organization. We tested the neurons for visual responses to stationary and moving stimuli and for changes in these responses produced by behavioral manipulations. All areas contain cells sensitive to stimulus orientation as well as neurons selective for the direction of stimulus movement; however, the majority of cells in all three regions are either broadly tuned or nonselective for these attributes. Nearly all cells respond to stimulus onset, a significant number also give a response to stimulus termination, and rarely a cell gives only off responses. Nearly all cells increase their discharge rate to visual stimuli. Receptive fields in the two retinotopically mapped regions, PI and PL, have well-defined borders. The sizes of these receptive fields show a positive correlation with the eccentricity of the receptive fields. The receptive fields in the remaining region, Pdm, are frequently very large, but with these large fields excluded, show a similar correlation with eccentricity. All pulvinar cells tested (n = 20) were mapped in retinal coordinates; the receptive fields are positioned in relation to the retina. We found no cells with gaze-gated characteristics (2), nor cells mapped in a spatial coordinate system. The response latencies in PI and PL are shorter and less variable than the latencies in Pdm. Active use of a stimulus can produce an enhancement or attenuation of the visual response. Eye-movement modulation was found in all three subdivisions in about equal frequencies. Attentional modulation was common in Pdm and was rare in PI and PL. The modulation is spatially selective in Pdm and nonselective in PI for a small number of tested cells. These data demonstrate functional differences between Pdm and the other two areas and suggest that Pdm plays a role in selective visual attention, whereas PI and PL probably contribute to other aspects of visual perception.

Animals↗
PubMed1984

Evoked potential augmenting and reducing: the methodological and theoretical significance of new electrophysiological observations.

Buchsbaum's (1976) evoked potential (EP) procedure reveals differences in the slope of P100-N140 amplitude changes with variation of stimulus luminance. Subjects are classed 'augmenters' or 'reducers', respectively, if their slopes are positive or negative. Psychological correlates of this slope index have been reported and it has distinguished psychiatric patient populations from healthy subjects. Data are presented which indicate that the augmenting-reducing slope differences are due to an early slow-wave. For augmenters, the major slow-wave deflection is of positive polarity. At the highest luminance, with a correspondingly shorter latency, the slow-wave increases the positive-going P100 deflection. At the lowest luminance, with a longer latency, it reduces the negative-going N140 deflection. This results in positive slopes. For reducers, the major slow-wave deflection is of negative polarity. This influences the measured P100 and N140 amplitudes in a manner opposite to that described for augmenters and results in negative slopes. Since these findings provide new insights concerning the nature of the Buchsbaum augmenting-reducing phenomenon, they have methodological and theoretical implications. It is concluded that the Buchsbaum procedure is an effective measure of slow-wave differences but that the reducing effect is difficult to explain in terms of Pavlov's concept of protective inhibition. An alternative 'opponent-process' explanation is offered.

Brain↗
PubMed1983

A case of neonatal herpes simplex with pneumonia.

A case of neonatal herpes simplex infection is discussed that presented as pneumonia, with subsequent development of skin lesions. The virus was isolated from skin scrapings. In spite of treatment with vidarabine, skin lesions continued to develop, and central nervous system involvement occurred. Acyclovir therapy led to prompt resolution of symptoms.

Acyclovir↗
PubMed1983

Structure of Witkin's Embedded Figures Test.

A number of reports have indicated that Witkin's Embedded Figures Test correlates with performance on standard intelligence tests. This finding was replicated in a recent factor analytic study when the test loaded substantially on a factor best representing the performance subtests of the Wechsler Adult Intelligence Scale (WAIS). However, the embedded figures also loaded on an uncorrelated factor, in addition to those normally associated with WAIS, which would relate well to Witkin's conception of psychological differentiation. These loadings on two uncorrelated factors suggested that the factorial structure of the Embedded Figures Test should be examined. An item analysis indicated a bi-factorial structure and, as presently constituted, the scale will provide misleading and ambiguous information.

Adolescent↗
PubMed1983

An analysis of human EEG responses in the alpha range of frequencies.

The diffuse thalamocortical system (DTS) can be represented by a simple 'lumped' model if near synchronous activity of thalamocortical 'circuits' is assumed. Such activity results in scalp potential changes that are manifest in the EEG. The model suggested by the anatomy and physiology of the DTS is also suggested by the dynamic character of the EEG and it is testable since it is possible to excite the DTS with a stimulus input and record the corresponding EEG response. Experiments carried out on 48 human subjects reveal that the model can account for most of the within- and across-subject amplitude variation of EEG evoked responses to sinusoidally modulated diffuse light. It can also explain phenomena specifically associated with stimulation of the DTS, namely 'after-discharges,' 'recruiting responses' and EEG 'alpha activity.' Most importantly, the model makes it possible to carry out a precise analysis of EEG responses to stimulation in terms that are neurophysiologically and psychologically meaningful.

Adolescent↗
PubMed1982

Detection by enzyme-linked immunosorbent assays of antibody specific for Pseudomonas proteases and exotoxin A in sera from cystic fibrosis patients.

Enzyme-linked immunosorbent assays were developed to measure serum antibody specific for Pseudomonas elastase, alkaline protease, and exotoxin A. Antibody responses to each Pseudomonas antigen were measured in cystic fibrosis (CF) patients who were not colonized with Pseudomonas aeruginosa, in those who were colonized, in those who were chronically infected with this organism, and in control subjects. Antibody levels for each antigen in the colonized and infected CF patients were higher than levels in uncolonized CF patients or non-CF control subjects. The antibody responses to elastase were similar in patients of the colonized and infected groups. However, infected CF patients had significantly elevated levels of antibody to exotoxin A (P less than 0.01) and alkaline protease (P less than 0.05) when compared with patients simply colonized with P. aeruginosa. These findings confirm that Pseudomonas alkaline protease, elastase, and exotoxin A are produced by Pseudomonas strains which colonize and infect CF patients. As an adjunct to established procedures (X-ray, microbiological culture, etc.), the antitoxin and anti-protease enzyme-linked immunosorbent assays may be clinically useful tests for differentiating colonized CF patients from those who have more severe Pseudomonas pulmonary infections.

ADP Ribose Transferases↗
PubMed1982

The reliability, validity, and utility of three data modes in assessing marital relationships.

Data from individual interviews, four questionnaires, and two analogue situations for 12 married couples were examined by six clinical judges and evaluated with regard to various aspects of interpersonal functioning. Orders of presentation were counterbalanced in a Latin square design. Ratings were made after each kind of data had been reviewed, after a case conference, and following discussion leading to consensus. Reliabilities were computed for the sets of variables and for each data mode. The convergent and discriminant validities of judgments based on the three data modes were examined by means of a multitrait-multimethod matrix. The utilities of the data modes and of increasing amounts of information were gauged by correlating partial estimates with average judgments of all judges based on all data following case conference. Among the findings were reasonably high levels of reliability for some aspects of interpersonal functioning but very low agreement regarding recommended treatment, quite high convergent validity across the three data modes, and modest but significantly superiority of the interview over the other procedures for assessing marital relationships.

Adult↗
PubMed1980

Behavioral enhancement of visual responses of prestriate neurons of the rhesus monkey.

Neurons in the superior colliculus, striate cortex, frontal eye fields, and posterior parietal cortex of the monkey respond to visual stimuli. Many of these cells discharge more intensely to a stimulus when it is to be the target for a saccadic eye movement than when fixation is maintained. We have demonstrated that such enhancement of the visual response is also present for cells in prestriate cortex. The prestriate effect is a modulation of the visual response and not a concomitant of oculomotor activity. It is present for eye movements away from as well as into the visual receptive field and is thus similar to that seen in striate cortex and different from that studied in the superior colliculus, frontal eye fields, and posterior parietal cortex. The visual responses of many prestriate cells habituate with repeated stimulation. When the monkey makes saccadic eye movements to a stimulus that is eliciting only a habituated response, the enhancement acts as a dishabituation which persists throughout the eye movement trials.

Animals↗
PubMed1978

Housekeeping: customized training program keyed to hospital's procedures, staff.

Thoughtfully developed, conscientiously applied housekeeping employee training programs are all too scarce. The program described was customized to fit an individual hospital's standard procedures, and it used volunteer models from among the workers to illustrate the video portion of the program. Recognition of employee merit and effective supervision and follow-up were two other key elements.

Hospital Bed Capacity, 500 and over↗