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Biomedical subjects

D R Thomas

Publications and source records attributed to D R Thomas.

At least 127 records · Page 7Linked to original sources
PubMed1982

Comparison of topical erythromycin 1.5 percent solution versus topical clindamycin phosphate 1.0 percent solution in the treatment of acne vulgaris.

Commercial topical solutions of erythromycin 1.5 percent and clindamycin phosphate 1.0 percent were evaluated in a randomized, double-blind, twelve-week comparison in sixty-six patients with moderate acne. Both treatment groups showed significant reductions of total lesions, inflammatory lesions, and papules. Additionally, the group using erythromycin 1.5 percent showed significant decreases in total noninflammatory lesions and closed comedones, and the group using clindamycin phosphate 1.0 percent showed significant reductions in pustules. The only statistically significant differences between the treatments were the greater reductions in closed comedones for those patients using erythromycin 1.5 percent and greater reductions in pustules for those patients using clindamycin 1.0 percent. Nearly two thirds of the patients in each group had a good or excellent overall response after twelve weeks. One erythromycin-treated patient discontinued treatment because his wife became sensitized to it. This reportedly also occurred with the use of topical clindamycin. Other side effects were minor or transient. In this study, topical erythromycin 1.5 percent and clindamycin 1.0 percent appeared to be clinically equivalent for treating moderate facial acne.

Acne Vulgaris↗
PubMed1982

Task specificity in nonspecific transfer and in extradimensional stimulus generalization in pigeons.

The theory of general attention predicts that true discrimination (TD) training will produce greater positive non- (stimulus-) specific transfer and sharper extradimensional stimulus generalization gradients than pseudodiscrimination (PD) training, because TD training establishes a set to discriminate (general attentiveness). Previous demonstrations have employed go-no-go (GN) discrimination training. In order to determine whether discrimination training per se is sufficient to produce the effects described, TD and PD groups of pigeons were trained in a successive-conditional (SC) discrimination. In Experiment 1, eight groups received TD or PD training between two line orientations in either an SC or a GN discrimination prior to transfer to either a true SC or a true GN discrimination between two colors. Discriminative performance in transfer was facilitated only when the original and transfer discriminations were of the same type. Experiment 2 replicated four of the conditions of Experiment 1 with procedural changes to make the transfer discrimination identical to that employed in previous "general attention experiments," with the same results. It is concluded that positive nonspecific transfer is primarily mediated by the transfer of task-specific learning rather than by the transfer of attentiveness. In Experiment 3, four groups were trained as in Stage 1 of Experiments 1 and 2, then given single-stimulus (SS) training with a chromatic stimulus, followed by a wavelength stimulus generalization test. Only TD-GN discrimination training produced sharp gradients, an effect leading to the conclusion that go-no-go discrimination training and stimulus generalization are closely related by task requirements rather than by attention. It is concluded that task-appropriate response tendencies probably mediate the effects observed.

Animals↗
PubMed1980

The use of time-interrelated covariates to predict survival following aortic valve replacement.

One hundred four patients survived isolated aortic valve replacement with the model 1200 prosthesis between 1965 and 1968, with a 12-year survival of 64%. Multiple regression survival analysis was employed in an attempt to determine which of 26 preoperative variables affected late survival and to devise a formula to predict survival for a given individual. The most important variables in the regression equation were right atrial mean pressure, etiology, and sex. The effect of the last two were found to vary with time over the 12-year post-operative period. An extension of the standard regression analysis technique was developed to incorporate time-related cofactors into the model. Based on the multiple regression model, 12-year survival was estimated to range from 92% to 14% for the best and worst combinations, respectively, of the three significant variables. The advantages of the regression method are outlined and the findings of other studies with regard to factors affecting survival after aortic valve replacement are summarized and discussed.

Adult↗
PubMed1978

The physician's assistant: a cloudy professional status.

Physician's assistants (PAs) are accepted by the rest of the medical community in varying degrees. Echoing this is the diverse legislation enacted by the states to handle PA certification, registration, and employment. It is generally agreed upon, however, that PAs can be of assistance in solving the manpower distribution problem in underserved areas.

Certification↗
PubMed1978

The central tendency effect in stimulus generalization: the effect of sex of subject.

Eighty male and 80 female college students were shown a stimulus light of 525 nm, following instructions to remember it, and then were immediately tested for generalization (recognition) with a successively presented set of stimuli including 525 nm and six longer wavelength values. Subjects rated each test stimulus on a 6-point scale ranging from "surely same" as the original stimulus to "surely different." Both men and women showed a central tendency shift. Although the stimulus perceived as most likely to be the original (the mode) shifted to 545 nm in both groups, the men showed a greater mean shift than the women. Shifting was nearly complete in both groups within the first series of test stimuli with the men shifting faster. These findings replicate a 1972 report by Giurintano of greater central tendency shift in men than in women in a line angle generalization task, challenging an assumed analogy between our generalization task and the rod-and-frame test, in which women typically show the greater distortion. The analysis of central tendency shift within the first test series reveals that it occurs much earlier than previously believed.

Discrimination, Psychological↗
PubMed1977

Survival with inoperable lung cancer: an integration of prognostic variables based on simple clinical criteria.

The objectives are to identify and integrate through regression analysis those fundamental clinical variables predicting survival of patients with inoperable lung cancer managed in a modern setting. Median survival time from first treatment in 129 patients with limited disease and 187 patients with extensive disease was 36 and 14 weeks, respectively. Within the proposed survival model for limited disease, weight loss was the major prognosticator followed by symptom status, supraclavicular metastases, and age. Within extensive disease, symptom status and age were dominant variables followed by weight loss and metastases to liver, opposite hemithorax, brain, and bone. Survival by cell type was similar within the limited and extensive disease groups. The data identify the essential factors which must be controlled or accounted for in studies analyzing survival as a dependent variable.

Age Factors↗
PubMed1977

Sustained action tetracycline preparation--tetrabid-organon blood level study.

A comparison of the plasma levels of tetracycline obtained whilst taking standard therapeutic doses of Tetrabid-Organon was made in twelve healthy volunteers. Two standard production batches were used in the study which was conducted under double-blind conditions. Sampling 12 hours and 8 hours after dosing showed no significant differences in plasma levels, with each batch. Even at these lowest levels satisfactory concentrations were rapidly obtained following initial administration, and were maintained when the drug was given at 12-hourly intervals. No side-effects of the drug were noted.

Adult↗
PubMed1977

Aortic valve replacement: a ten-year follow-up of non-cloth-covered vs cloth-covered caged-ball prostheses.

From 1965 to 1976, 721 isolated aortic valve replacements were performed at the University of Oregon hospitals, utilizing Starr-Edwards caged-ball prostheses. Three models of aortic prostheses were introduced during this period: a non-cloth-covered model has been in continuous use since 1965; a cloth-covered model was begun in 1968 and has been supplanted by the modified composite-strut or "track" model since 1972. The 5-year actuarial survival rate for operative survivors is about 80% for both non-cloth-covered and cloth-covered valves, while the 10-year survival is 61%, based on the older model only. The actuarially-determined percentages of patients experiencing significant thromboembolic episodes (i.e., all except transient ischemic episodes) at 5 years are 7% for the cloth-covered and 9% for the non-cloth-covered model. If transient ischemic attacks are included, the cloth-covered model has only an 8% incidence at 5 years compared to a 22% incidence for the older model. However, the cloth-covered valves are subject to a higher risk of reoperation because of the possibility of cloth injury. The "track" valve, therefore, was designed with exposed metal on the inner surface of each strut to prevent ball-cloth contact. In 107 patients (mean follow-up period 1 year) receiving anticoagulation, this prosthesis has maintained the same low incidence of thromboembolism as the previous cloth-covered model, with no reoperations for valve failure.

Aortic Valve↗