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Biomedical subjects

D R Thomas

Publications and source records attributed to D R Thomas.

At least 145 records · Page 8Linked to original sources
PubMed1976

Bleomycin (NSC-125066) followed by cyclophosphamide (NSC-26271), vincristine (NSC-67574), methotrexate (NSC-740), and 5-fllorouracil (NSC-19893) for non-oat cell bronchogenic carcinoma.

The in vivo observation that bleomycin may be used as a synchronizing agent provides the basis for testing 4 days of continuous bleomycin infusion followed by 5 days of intensive chemotherapy with cyclophosphamide, vincristine, methotrexate, and 5-fluorouracil. Thirty-eight patients with extensive non-oat cell bronchogenic carcinoma (adenocarcinoma[17 patients], squamous cell carcinoma[14 patients], and poorly differentiated carcinoma [seven patients]) were registered for chemotherapy. There were 11 patients with 50% regression of all measurable lesions and four with improved but poorly measurable radiographic lesions, providing a crude response rate of 39% (15 of 38 patients). An overall survival median of 19 weeks compares favorably with Veterans' Administration Lung Cancer Study Group control data, but was not substantially better than our own historical controls (P = 0.15). The median survival for responders was 36 weeks compared to 16 weeks for historical controls (P = 0.001) and 12 weeks for nonresponders (P less than 0.001).

Adenocarcinoma↗
PubMed1975

Effects of stimulus similarity in discrimination training upon wavelength generalization in pigeons.

Thirty pigeons were given variable interval training to peck a 555-nm. light and then were tested for wavelength generalization. The subjects were later assigned to 1 of 3 groups, matched for both relative generalization slope and response rate. One group then received successive discrimination training between the 555-nm. stimulus (S+) and a vertical white line on a 555-nm. background (S minus); another group experienced the same S+ but a vertical white line on a black background as S minus. A third group received a comparable amount of single stimulus training with the 555-nm. value. On a second wavelength generalization test, the first group yielded greater sharpening of generalization than the second group, whereas the third group showed no change from Test 1. These results indicate that the sharpening of generalization gradients by discrimination training is directly related to the similarity of the discrimination training stimuli.

Animals↗
PubMed1974

Relative and absolute density of reinforcement as factors influencing the peak shift.

Four groups of six pigeons each were given nondifferential training on multiple variable-interval variable-interval reinforcement schedules and then were switched to differential training involving a multiple schedule in which reinforcement density was reduced in one of the two components. The multiple schedules used in the four groups had mean interreinforcement intervals of 1 min and 1 min in the two components changed to 1 min, 5 min; 2.5 min, 2.5 min changed to 2.5 min, 5 min; 12 sec, 12 sec changed to 12 sec, 24 sec; and 12 sec, 12 sec changed to 12 sec, 60 sec. In subsequently administered wavelength generalization tests, some peak shifts were observed in each condition and occurred occasionally in the absence of behavioral contrast or rate reduction in the less-reinforced component. The best predictor of peak shift was a high proportion of total responses emitted during the more-reinforced component at the end of differential training.

Journal Article↗