Autonomic Nervous System Function and Essential Hypertension: Individual Response Specificity With and Without Beta-Adrenergic Blockade

The aim of the present research was to study individual response specificity in 22 male patients having essential hypertension (HT) and to compare these patients with age-matched male normotensive controls (NT). Four stimuli, letter identification, mental arithmetic, cold pressor and isometric exercise, were administered while recordings were made of: systolic and diastolic blood pressures, heart rate, respiration, forearm and hand blood flows, and skin conductance level and fluctuations. After each session urine samples were collected and epinephrine and norepinephrine levels were analyzed. Twelve subjects in the HT group were given beta-adrenergic blocking agents and retested 1 to 21 months (X?= 12 months) after the first session. Each response was standardized, using NT as the reference group. Intraclass correlations were computed to evaluate whether HT males reacted with a more consistent hierarchy of responses than did NT. Intraclass correlations were significantly higher among the patients than in the control group, regardless of whether the blood pressure response was included or excluded in the computation of the intraclass correlations. Thus, we conclude that male HT patients show more individual response specificity than NT controls. Beta-adrenergic receptor antagonists reduced levels of cardiovascular activity and attenuated reactivity but did not affect amount of specificity. Thus, intraclass correlations provide unique and useful information, since they are not related to blood pressure reactivity or to urinary catecholamine levels, nor affected by beta-adrenergic blockade.     

The Effects of Discrimination Training on Voluntary Control of Cephalic Vasomotor Activity

The present study was conducted to test Brener's calibration theory of visceral learning. It was hypothesized that training in discrimination of cephalic vasomotor responses would enhance acquisition of voluntary and biofeedback control of cephalic vasomotor response. Four groups were given discrimination training to detect either constriction, dilation, both constriction and dilation, or given false feedback. All groups were then given biofeedback training in constriction. All groups were assessed on discrimination accuracy, acquisition of biofeedback control of constriction, and voluntary control of dilation and constriction. The results indicated that discrimination of cephalic vasomotor responses can be learned and that this skill facilitates the acquisition of biofeedback and voluntary control of vasomotor responses. This facilitation occurs only if discrimination training is given for the specific response to be learned. The data suggest that discrimination of the relevant response is a necessary but not sufficient condition for acquisition of voluntary control in biofeedback learning.     

Two Measures of Auditory Evoked Response Amplitude and Their Relationship to Background EEG

All-night sleep EEG and auditory evoked responses (AERs) were recorded in 8 children whose ages ranged from 27 to 60 months. EEG intensity was measured by means of a Drohocki-type integrator. Two measures of evoked response amplitude were calculated: the peak-to-peak amplitude of the P₂N₂ component, and a multiple-component amplitude measure of the first 500 msec of the response. Both amplitude measurements were found to correlate well with each other. Changes in EEG intensity between subjects were not correlated with changes in AER amplitude, but a number of correlations between AER amplitude and EEG intensity were found within individual subjects. Further analysis suggested the latter finding might be a result of the presence of “unaveraged’EEG in individual AER plots. It is concluded that little correlation exists between AER amplitude and EEG intensity in children during sleep.     

Imagery Vividness Affects Habituation Rate

In order to investigate the effect of individual differences in imagery vividness on habituation rate, 14 subjects were threatened with receiving and then imagined receiving an electric shock. Subjects first habituated to a tone which was then used as an auditory signal for the shock threat and the imagined shock. The skin conductance response (SCR) was used to follow the course of habituation. Results demonstrated that subjects with non-vivid imagery habituated to the tone more rapidly than subjects with vivid imagery when the tone was associated with imagining an electric shock. Implications of this finding for therapeutic techniques using instructed imagery are discussed.     

On the Shift from Anticipatory Heart Rate Deceleration to Acceleratory Recovery: Revisiting the Role of Response Factors

The influence of inducing motor responses of low and high force at different times in the cardiac cycle was examined. A handgrip response was used which allowed the separation of response initiation from response completion. Based on earlier work, we expected initiation, rather than completion, to initiate poststimulus cardiac acceleration. We also thought that preparation for a high force response might alter preparatory changes of interbeat interval differently from preparation for a low force response. Fifteen college-aged male subjects performed a warned reaction time task in which a visual stimulus signalled a handgrip requiring either a high or a low force to close. NoGo trials in which an inhibit signal was presented occurred on 12% of the trials. Stimuli occurred either on the R-wave of the electrocardiogram or 300 ms later. Reaction speed was varied in different trial blocks by rewarding response times of 200 ms (+/- 50 ms), 300 ms, or 400 ms. Results based on the timing of response initiation were essentially identical to those based on the timing of response completion. High force relative to low force was associated with both earlier response initiation and earlier cardiac acceleration. Force did not alter preparatory cardiac deceleration. Force and response speed did, however, alter the level of heart rate after response occurrence. Thus, response initiation (or an earlier response process) appears to induce a cardiac acceleration whose level is influenced by the speed and force of the motor response.     

CORRELATION OF SKIN POTENTIAL AND SKIN RESISTANCE MEASURES

Simultaneous measurements of skin potential (SP) and skin resistance (SR) obtained from 20 male and 20 female adult subjects during 2 sessions held 2 to 9 days apart were used in studying (1) the correlation of change measurements and prestimulus level in the two measures, and (2) the amount of correlation between SP and SR using both simple difference and residual change scores in which the regression of poststimulus values on initial level (prestimulus) has been controlled. Correlations within Ss and correlations among Ss showed large individual variability, correlation differences between males and females, and high correlation between SP and SR change scores. Although the law of initial value (LIV) seemed to have little applicability to the measurement of electrodermal responses, the results underscored the need to control for contamination of change measures by initial level regardless of direction.     

Repeated immunization with plasmid DNA formulated in poly(lactide-co-glycolide) microparticles is well tolerated and stimulates durable T cell responses to the tumor-associated antigen cytochrome P450 1B1

Injection of microparticle-encapsulated DNA elicits immune responses to plasmid-encoded antigens in mice and humans. Cytochrome P450 CYP1B1 (CYP1B1) is a member of the CYP1 P450 enzyme family that is overexpressed in a variety of solid tumors. The work described herein was performed to study the kinetics of stimulating T cell responsiveness with an encapsulated DNA encoding CYP1B1 and provides support for the clinical development of this formulation. Immunization of HLA-A2/Kb transgenic mice with human CYP1B1 encoding plasmid DNA formulated in poly(lactide-co-glycolide) (PLG) microparticles elicits CD8+ T cells that respond to human CYP1B1-positive target cells. The duration of the immune response, the effect on the immune response of multiple injections, and the safety of repeated injections were studied. These results show that the PLG-encapsulated DNA therapeutic elicits durable immune responses to CYP1B1, the responses are dependent on repeat immunization, and that the formulation is well tolerated.     

Genetic and light intensity effects on the activity and emigratory behavior of the house fly,Musca domestica (L.)

The emigratory behavior and locomotor activity of yellow-eyed (y/y), wildtype (+/+), and heterozygous (+/y) house flies was examined at 8 fc (86 lx) and 1600 fc (17,223 lx) light intenstities. At 8 fc, emigration rate and activity of the y/y flies was similar to that of the +/+ and +/y flies. However, at 1600 fc, the y/y flies emigrated at twice the rate and showed an activity of about one-third that of the other genotypes. The behavior of the +/+ and +/y flies remained similar regardless of the experimental design or light intensity. The excessive neural stimulation by high-intensity light resulting from reduced shielding pigments led to behavioral modifications in the visual and tactile responses of the y/y flies.This research was supported in part by grants from the CUNY Faculty Research Award Program (No. 1103) and NIH Biomedical Research Support Grant 5-S05-R-07064.