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Biomedical subjects

C Mandell

Publications and source records attributed to C Mandell.

32 records · Page 2Linked to original sources
PubMed1975

The response of the local immunoglobulin system to malignant lesions of the stomach. A new diagnostic test.

The response of the local secretory immunoglobulin system to tumor antigens was studied in 71 patients suspected of harboring a gastric malignancy. Gastric aspirates were obtained by fiberoptic endoscopy and measured on single radial immunodiffusion plates (Behring Diagnostics). Patients with malignant neoplasms of the stomach were divided into Type I and Type II lesions, based on the extent and stage of the disease. Secretory IgA titers were elevated in all patients with a Type I malignant tumor confirmed by histologic examination; mean 6.1 mg/100 (SD +/- 3.7 mg/100). This leads us to believe that the host's response to malignant cells of the gastrointestinal system is an altered and elevated secretion of IgA. Evaluation of local immunoglobulin titers may be of value when used in conjunction with other diagnostic modalities in determining the nature of gastrointestinal lesions, particularly when the lesion is not metastatic or massively involving the gastric wall.

Adult↗
PubMed1975

Differential reinforcement and signal detection.

Reinforcement was introduced for responses normally treated as errors in signal-detection procedures. The first experiment used a standard two-response discrete-trial procedure with no reinforcement for errors. Results showed that rats altered their response biases but maintained constant sensitivity to visual signals when reinforcement probabilities varied, and that their sensitivity depended on the physical difference between signals, in accordance with the predictions of signal-detection theory. Experiment II, with rats, and Experiment III, with pigeons, demonstrated that sensitivity decreased in this procedure when reinforcement was scheduled for errors with the signals held constant, despite independence of overall number of reinforcers and sensitivity. Experiment IV, with rats, replicated the decrease in sensitivity in a continuous procedure employing only one response. The decrements in sensitivity were similar across Experiments II, III, and IV, and accorded well with earlier research. Thus, contrary to a fundamental assumption of signal-detection theory, estimates of sensitivity are not always invariant with respect to the outcomes of responding, but depend on relative reinforcement of correct responses.

Animals↗
PubMed1974

Brain scanning.

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Angiography↗
PubMed1968

Discriminative control of "attention".

Three pigeons were trained to discriminate between two tones differing in frequency in the presence of light of one color (A), and not to discriminate between the tones in the presence of light of another color (B). Generalization functions that were determined in the presence of light A showed control of behavior by the frequency of the tone; those determined in the presence of light B did not.

Animals↗