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Biomedical subjects

D R Thomas

Publications and source records attributed to D R Thomas.

At least 181 records · Page 10Linked to original sources
PubMed1967

Response patterning during stimulus generalization in the rat.

Nine rats were trained to bar press in the presence of a clicking sound of 6.67 cps (S(D)) for 1-min variable-interval food reinforcement randomly alternated with a clicking sound of 20 cps (S(Delta)) signifying extinction. After a criterion of 90% of total responses in the presence of the S(D) was obtained, a generalization test was administered, including values of 6.67, 10.00, 13.33, and 20.00 cps, with responses in the presence of the S(D) continuing to be reinforced during testing. The test yielded a gradient of response strength with rate highest in the presence of the S(D) and decreasing with increasing distance from this value. An interresponse time (IRT) analysis of responding during generalization testing revealed no systematic differences in modal IRT category or in median IRT to the different test stimuli. Mean IRT was lowest in the presence of the S(D) and increased systematically with increasing distance from this value, supporting the hypothesis that the generalization gradient of response rate is primarily the result of an increasing proportion of "long" IRT responses to stimuli increasingly distant from the S(D).

Animals↗
PubMed1966

Stimulus control in pigeons based on proprioceptive stimuli from floor inclination.

Two groups of pigeons trained to peck a dimly illuminated disc in an otherwise dark experimental chamber with the floor horizontal (0 degrees tilt) or inclined 30 degrees to the left, respectively, show decremental generalization gradients of response rate when the floor inclination is varied from its training position. Discrimination training in which food reinforcement is available under one floor tilt condition but not under another steepens the slope of such gradients. In a secondv experiment, pigeons reinforced for pecking when the floor was tilted 10 degrees or 20 degrees and not reinforced under the alternative condition showed steep gradients with maximal responding displaced from the reinforced stimulus.

Animals↗
PubMed1966

A comparison of different measures of response strength in the study of stimulus generalization.

In Experiment 1, three pigeons were given variable interval training to peck at a light of 550 mmu and then were tested for stimulus generalization in extinction to several different wavelengths. A gradient was obtained for latency of the first response in each test period, for the number of test periods in which responding occurred, and for the measure of response rate. When the response rate gradient was corrected for differences in initial latency and in number of responded trials, the change was minimal, indicating that the major component of response rate as usually measured is rate of responding having once responded. In Experiment 2, three other pigeons were trained to respond to 550 mmu (for variable interval reinforcement) and not to 570 mmu (extinguished). Analysis of generalization gradients dictated the same conclusion as that reported for generalization following single stimulus training.

Animals↗
PubMed1966

Investigations of a mirror-image transfer effect in pigeons.

In two separate experiments, pigeons trained binocularly to peck a key on which an oblique line (e.g., 60 degrees counter-clockwise rotation from horizontal) was projected yielded bi-modal angularity generalization gradients in extinction, with peaks of responding at both the training stimulus and its mirror image (in this case 120 degrees ). This mirror-image transfer effect may be analogous to an "octave effect" in auditory generalization, but Mello's finding of a mirror-image reversal transfer effect following monocular training in pigeons suggests an alternative interpretation.

Animals↗
PubMedDate not supplied

Accidental hypothermia in the sunbelt.

Hypothermia in colder climates in the United States occurs predominately as a result of exposure of alcoholics to cold outdoor temperatures. Among 24 cases of accidental hypothermia occurring at a university medical center in the deep South, differences in clinical presentation were identified. In contrast to experience in colder climates, 17/22 cases (76%) developed at home. Alcohol was a factor in only 8/24 (33%). The elderly were at greatest risk, accounting for 16/24 patients (65%). Factors suggested to account for the high incidence of hypothermia in the elderly include abnormal temperature perception or regulation, intercurrent illness, social isolation, inadequate housing, and poverty. Coexisting medical conditions were identified as a potential cause of hypothermia in only 10/24 of these patients (42%). Social isolation was not a strong predictor, with 6/17 of the elderly (35%) living alone. Death occurred in 9/24 patients (37%), but survival could not be predicted from admission temperature, hypotension, anemia, or serum glucose. Since extreme cold temperatures are infrequent in the deep South, identified differences in demographics may be due to inadequate housing or lack of preparation for cold weather dangers.

Accidents↗
PubMedDate not supplied

Disposable insulin syringe reuse and aseptic practices in diabetic patients.

Diabetic patients are traditionally taught to discard plastic syringe/needle units after a single use and to employ aseptic technique for administering insulin injections. We surveyed 87 diabetic outpatients for compliance with aseptic recommendations. We then studied prospectively the effects of reusing disposable syringes in 56 diabetic patients who reused syringes a mean of 6.6 times for 8.3 months and an aggregate of 23,664 injections. Almost half (49%) of diabetic patients in a combined university clinic and private practice reused supposedly disposable insulin syringes a mean of 3.9 times. Compliance with standard aseptic precautions was poor, with only 29% of patients following recommended practices. No adverse effect of syringe reuse was identified. The authors conclude that diabetic patients frequently reuse disposable syringes, without apparent harmful effect.

Asepsis↗
PubMedDate not supplied

Nutritional aspects of wound healing.

Proper nutrition is essential to prevent the development of pressure ulcers and to support adequate and timely wound healing. Additionally, research and clinical observation suggest nutrients play a major role in wound healing. How the nutrients Vitamin A, Vitamin C, zinc, calories, protein, and fluids are used in wound healing and recommendations regarding use of supplements are discussed in this article.

Community Health Nursing↗
PubMedDate not supplied

A prospective study of outcome from protein-energy malnutrition in nursing home residents.

To study recovery from protein-energy malnutrition in patients newly admitted to a chronic care facility, biochemical and anthropomorphic malnutrition indicators were measured prospectively over a 2-month period. Subjects were observed for a mean of 76 +/- 18 days after admission. Factors which might affect nutritional status including method of feeding, energy prescribed, use of supplemental feedings, assistance in eating, and amount of diet consumed were recorded. Confounding variables including illness, mental status, functional status, or prescription drugs were evaluated for their impact. On the basis of an empiric nutrition score, 54% of newly admitted residents were malnourished. Improvement in nutritional score occurred in 63% of malnourished patients remaining in the facility whereas 37% remained malnourished. Two related factors, percentage of diet consumed and degree of assistance required in eating, were important differences in the outcome of patients remaining malnourished. Interventional studies to determine whether outcome can be improved by more aggressive feeding methods or by feeding teams need to be undertaken.

Aged↗
PubMedDate not supplied

Medical services provided at the 1982 Southern Open Golf Tournament.

This study describes the medical services provided the players, players' families, caddies, Professional Golf Association (PGA) officials, tournament workers, and spectators during the 1982 Southern Open Golf Tournament. One first aid center, staffed by one physician and one nurse, was available to approximately 12,000 people during the 7 day event. The facility was stocked with routine diagnostic and therapeutic supplies, as well as routine and emergency drugs. Of the 92 patients seen, only one, who presented with a seizure, required hospital management. Spectators accounted for 20% of the visits. The remaining visits were by the tournament population for acute care. It was concluded that additional orthopaedic supplies needed to be readily available. Additional emergency equipment and drugs are recommended. The available and needed supplies should provide a reference for stocking first aid stations at future similar outdoor events that attract large crowds with varied medical needs.

Emergency Medical Services↗
PubMedDate not supplied

Pharmacological characterisation of [35S]-GTPgammaS binding to Chinese hamster ovary cell membranes stably expressing cloned human 5-HT1D receptor subtypes.

[35S]-GTPgammaS binding has been used to study the function of cloned human 5-HT1D receptor subtypes stably expressed in chinese hamster ovary (CHO) cells. 5-HT stimulated [35S]-GTPgammaS binding to membranes from cells expressing 5-HT1Dalpha or 5-HT1Dbeta receptors. In membranes containing 5-HT1Dbeta receptors, 5-CT and sumatriptan stimulated binding to a similar extent as 5-HT while yohimbine, metergoline and 8-OHDPAT were partial agonists. The order of potency for agonists was 5-CT > 5-HT > metergoline > sumatriptan > yohimbine > 8-OHDPAT. The stimulation of binding by 5-HT in membranes containing 5-HT1Dbeta receptors was potently antagonised by methiothepin (pA2 8.9 +/- 0.1). The overall pharmacological profile for the human 5-HT1Dbeta receptor, defined using [35S]-GTPgammaS binding, agreed well with that reported for inhibition of forskolin-stimulated adenylyl cyclase. In addition, methiothepin and ketanserin inhibited basal [35S]-GTPgammaS binding to membranes containing 5-HT1Dalpha or 5-HT1Dbeta receptors, suggesting that these compounds show negative efficacy at 5-HT1D receptor subtypes. The data show that [35S]-GTPgammaS binding is a suitable method for studying the interaction between cloned human 5-HT1D receptors and G-proteins.

8-Hydroxy-2-(di-n-propylamino)tetralin↗