Biomedical subjects
Publications and source records attributed to D R Thomas.
Times in remission from affective illness were prolonged during treatment with lithium carbonate and carbamazepine, but lithium was the more effective. Similar global scores for the two drugs suggested that other factors may determine their acceptability.
In Experiment 1 (within subjects) and Experiment 2 (between subjects) it was shown that the sequential training of pigeons on a color discrimination and then on its reversal, each in a different floor-tilt/texture context, failed to produce conditional control of discriminative performance by those contexts. Daily alternation between the two problems (with correlated contexts) was successful, however. In each of these experiments conditional control was better reflected in generalization test performance in extinction than during sessions of training with reinforcement.
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The response of patients with major depressive illness to citalopram of amitriptyline was compared in a double-blind multi-centre trial. No differences in efficacy were observed, but citalopram had less hypnotic effect, and a remarkably lower profile of side-effects.
Three experiments examined the assertion that presession handling cues that accompany training with reinforcement might account for spontaneous recovery when they reoccur following extinction. In Experiment 1, after extensive training on a variable-interval schedule, key pecking in pigeons was extinguished following either normal or distinctively different handling and transportational cues. Those cues resulted in enhanced spontaneous recovery 24 hr later when normal cues were reinstated. In Experiment 2, however, subjects tested following the normal handling cues showed no more spontaneous recovery than did subjects that spent the entire extinction-test interval in the experimental chambers and thus were tested without handling cues altogether. In Experiment 3, a group whose test for recovery began 10 min after being placed in the chambers yielded as much spontaneous recovery as did a group tested normally. Furthermore, a group for which extinction began at mid-session and for which handling therefore could not be a discriminative cue for extinction showed no more spontaneous recovery than did the other two groups. Handling cues thus contributed to spontaneous recovery only after explicit discrimination training, as provided in Experiment 1.
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Trichostasis spinulosa is a common disorder of follicular hyperkeratosis that is often confused clinically with similar disorders, such as keratosis pilaris and eruptive vellus hair cysts. Six patients from the UTMB dermatology clinic who had trichostasis spinulosa are presented. Two of the six also had keratosis pilaris and one had eruptive vellus hair cysts. The present study was undertaken to compare and contrast the clinical presentation and histopathologic appearance of these three disorders. The results of the study and review of the literature revealed differences in distribution of lesions and microscopic appearance of follicular and histopathologic material.
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Two patients, a father and son, with pachyonychia congenita were treated with orally administered isotretinoin because the extreme deformity and discomfort associated with their massive keratoderma interfered with their work and school, respectively. While clinical benefits could not be sustained, electron microscopic findings compatible with suppression of abnormal keratinization were observed. In addition, skin biopsy samples were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the gels were then subjected to a lectin overlay technique with concanavalin A labeled with iodine 125. The distribution of specific glycoproteins was found to be different for lesional as against normal epidermis. The procedure was repeated after oral treatment with isotretinoin. The labeled glycoprotein pattern of the lesional epidermis was clearly distinguishable from both the pretreatment lesional and the normal epidermis; it was mostly intermediate between the two. The normal epidermis was virtually unaffected by the retinoid treatment.
Physical training in the form of long-term nonexhaustive daily exercise was studied as a means of regulating fatty acid biosynthesis. Male rats were required to swim for periods up to 90 min/day. The exercise was carried out 6 days/wk for approximately 11 wk. Hepatic fatty acid biosynthesis and acetyl-CoA carboxylase [acetyl-CoA: CO2 ligase (EC 6.4.1.2)] activities were compared with nonexercised rats. At the end of the training period the exercised rats had a lower rate of fatty acid biosynthesis activity and a lower rate of acetyl-CoA carboxylase activity. The difference in acetyl-CoA carboxylase activity was due to a change in maximal velocity with no significant change in the Michaelis constant for acetyl-CoA. Untrained rats were subjected to a single bout of exercise. They also exhibited lower rates of fatty acid biosynthesis and acetyl-CoA carboxylase activities compared with nonexercised rats. However, the lower rates of these enzyme activities were sustained longer in the physically trained rats compared with the exercised untrained rats after the cessation of exercise. These results implicate acetyl-CoA carboxylase as a control site in the regulation of hepatic fatty acid biosynthesis by both physical training and acute exercise in rats. Possible inhibitory mechanisms are discussed.
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