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Biomedical subjects

R Simons

Publications and source records attributed to R Simons.

At least 37 records · Page 2Linked to original sources

Strategies of arousal control: biofeedback, meditation, and motivation.

A series of four experiments assessed the effects of instructions to lower heart rate on heart rate change and general arousal reduction. Various conditions of biofeedback, cognitive load, incentive, knowledge of results, and the experimenter-subject relationship were tested. Experiment 1 compared physiological responses to the delivery of direct organ feedback (i.e., heart rate) with responses to electromyographic biofeedback from the frontalis muscle area and with responses to a nonfeedback tracking task. The results suggest that neither heart rate nor muscle tension feedback is an especially powerful method for achieving sustained reductions in heart rate. Furthermore, although some specificity of physiologic pattern is apparent, biofeedback is no more effective in lowering general activation level than simple instructions to relax accompanied by a general knowledge of results. The second experiment was designed to assess the role of cognitive load in arousal reduction. Heart rate biofeedback was compared with a procedure involving minimal external information processing--the secular meditation exercise of Wallace and Benson. The results indicated a clear superiority for the meditation strategy in effecting reductions in cardiac rate and lowering activation. However, in a third experiment, meditation subjects lowered heart rate much less than observed in the previous study, and this time the reduction did not exceed that achieved by feedback subjects. Subsequent analysis suggested that the quality of the subject-experimenter relationship (active-supportive vs. formal-distant) was a significant variable in accounting for outcome differences. The above hypothesis was supported by a fourth experiment. Under conditions of high subject-experimenter involvement, the superior meditation performance of Experiment 2 was reproduced; under low-involvement conditions the Experiment 3 result of no difference between training groups was obtained. The findings suggest that the effectiveness of any method for achieving relaxation (or physiological control) rests on a complex interaction between informational and motivational imperatives of the stimulus context and definable aspects of the interpersonal exchange between subject and experimenter. This research raises serious questions about the effectiveness of the usual biofeedback paradigm as an aid to arousal reduction and the cost efficiency of its applications in the clinical situation. Furthermore, these results demonstrate the great power in relaxation experiments of psychosocial and other moderator variables, and signal the practical difficulty of their control when these variables appear to be as potent in changing physiology as the primary training methods.

Arousal

Enhancement of activity against influenza viruses by combinations of antiviral agents.

In an investigation of alternative therapeutic approaches for the treatment of influenza virus infections, the antiviral activities of rimantadine hydrochloride, amantadine hydrochloride, ribavirin, and combinations of these drugs were assessed in vitro. Madin-Darby canine kidney cell monolayers were inoculated with recent isolates of influenza viruses at low multiplicities of infection, and virus titers were determined after 24 h. The combination of rimantadine and ribavirin resulted in an enhanced antiviral effect (a decrease in virus titer of > 1.0 log10 plaque-forming unit per ml at 24 h relative to the maximal effect of a single drug) against A/USSR/90/77/H1N1, A/Texas/1/77/H3N2, A/New Jersey/76/HSW1N1, and A/PR/834/H0N1 viruses. The degree of inhibition depended on the virus strain used, the drug concentrations, and the virus inoculum. Amantadine and ribavirin showed enhanced activity. Ribavirin in combination with high (50 micrograms/ml), but not low (1.56 to 25 micrograms/ml), concentrations of rimantadine showed an enhanced antiviral effect against B/Hong Kong/72 virus. An assay of Madin-Darby canine kidney cell proliferation in the presence of drugs showed that the enhanced inhibitory effect of drug combinations was not due to increased cytotoxicity.

Antiviral Agents

The electrical characteristics of fixed charge membranes: solution of the field equations.

A theoretical analysis is made of the electrical characteristics of a membrane containing two fixed charge regions, of opposite sign, in contact. Profiles of ion concentrations, electrostatic potential, space charge density, as well as the voltage-current characteristics were obtained by numerical integration of the field equations on a computer. Comparison with the predictions of an earlier analysis of this system (Coster, 1965) shows that the latter is valid to a good approximation for membranes > 70 A in thickness. In particular the form of the electrical characteristics, including the punch-through effect, have been verified by the computer analysis. The range of useful validity of the earlier analysis, the use of Boltzmann statistics when currents are present, and variation of membrane capacitance with applied potential, are discussed in the light of the results obtained.

Computers