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Biomedical subjects

J L Howard

Publications and source records attributed to J L Howard.

At least 55 records · Page 3Linked to original sources
PubMed1979

The Geller-Seifter conflict paradigm with incremental shock.

The typical Geller-Seifter conflict paradigm for predicting clinical efficacy of anxiolytics is a mult VI/CRF schedule in which response rates in the CRF (conflict) portion are depressed by response-contingent electric shock. In 1-h sessions, anxiolytics raise the depressed conflict rates. Recently it was shown that replacing the single shock level with an arrangement whereby shock begins at zero and is increased with each response in the conflict portion produced more orderly data and facilitated training and maintenance of experimental subjects; chlordiazepoxide was the test drug. In the present study, those results are replicated in 30-min sessions, and the incremental paradigm is demonstrated to be as specific for anxiolytics as the standard Geller-Seifter paradigm. The possibility of very short sessions is suggested.

Animals↗
PubMed1978

Anti-lung antibodies associated with human lung allografts.

Serum specimens from 4 patients who had had a lung allograft were examined for anti-lung antibodies. Two patients developed antibodies after transplantation, and in 2, the antibodies increased in titer after an allograft. The absorption of the anti-lung antibody by fetal lung cell cultures, in contrast to the failure of absorption by kidney cell cultures from the same fetus, indicates that the antibody is lung specific.

Antibody Specificity↗
PubMed1977

Blood pressure and cardiac changes during signalled and unsignalled avoidance in dogs.

Alterations in blood pressure (BP) during two aversive behavioral tasks were studied in five chronically-prepared dogs. During a signalled-avoidance task, BP levels were not altered, although heart rate (HR) increased. While propranolol (0.3 mg/kg, IA) led to slight increases in resting pressure, and phenoxybenzamine (1.0 mg/kg) reductions, the tachycardia at avoidance onset was not affected. Exposure to an unsignalled-avoidance task led to elevated diastolic BP levels during a preavoidance period and to increases in systolic BP, HR and aortic dP/dt at the inception of the avoidance session. Again, neither drug affected the tachycardia during avoidance, but both agents precluded BP and aortic dP/dt increases. Patterns of intercorrelations among cardiovascular variables were similar for both tasks, and suggested that the basis of the BP maintenance shifted from vasomotor to cardiac control during the avoidance periods. The differential cardiovascular adjustments during these tasks could not be accounted for in terms of differences in response rate. Rather, the critical variable seemed to be the amount of feedback the animal received for responding.

Animals↗
PubMed1976

Effect of beta-phenylethylamine and d-amphetamine on electrical self-stimulation of brain.

beta-phenylethylamine (PEA) has been viewed as amphetamine-like in its effects on behavior. Support for this putative similarity of action has been derived primarily from observations that both of these structually related compounds increase locomotor activity in a dose-related manner and at higher doses evoke stereotypies. Since d-amphetamine (d-A) produces a dose-related increase in the rate of bar pressing for electrical stimulation of the medial forebrain bundle, the effect of PEA on this behavioral paradigm was examined. Male Long-Evans rats implanted with bipolar electrodes self-administered 250 msec 60 Hz constant current sine wave trains over a 30-70 micronA range of intensities in daily 20-min tests. Over a range of 1-40 mg/kg IP of PEA, a dose-related decrease in self-stimulation rate was observed; pretreatment with para-chlorophenylalanine or alpha-methyl-para-tyrosine did not alter the response to 2.5 or 3o mg/kg IP of PEA. Since within the dose range of PEA used in this study a dose-related increase in locomotor activity was observed, and since d-A increases self-stimulation rate at doses that increase locomotor activity, it would seem that there are qualitative differences in the actions of d-A and PEA on behavior.

Animals↗
PubMed1975

Neuromuscular blocking drugs and heart rate changes after direct nerve stimulation and during classical conditioning in cats.

Two experiments investigated cardiovascular responses to several common neuromuscular blocking compounds. Experiment 1, employing 16 cats, assessed ganglionic transmission in sympathetic and parasympathetic systems controlling heart rate and blood pressure after d-tubocurarine chloride (d-T.C.), dimethyl d-tubocurarine iodide (D. d-T.I.), succinylcholine chloride (SC), or saline. Cardiovascular responses to sympathetic stimulation were essentially unaffected at drug levels that blocked evoked electromyograms; however, vagally evoked bradycardia and corresponding blood pressure decrease were blocked by d-T.C. and redduced by D. d-T.I. and SC. Experiment 2 compared heart responses of 12 cats under the same blocking compounds during differential classical aversive conditioning. Differential conditioned responses and unconditioned responses occurred under D. d-T.I., less under SC, but not under d-T.C. However, animals trained under d-T.C. and tested under D. D-T.I. showed differential conditioned responses.

Acoustic Stimulation↗