Biomedical subjects

J R Jennings

Publications and source records attributed to J R Jennings.

At least 55 records · Page 3Linked to original sources

PubMed1993

Peripheral thermal responsivity to facial cooling during sleep.

A recently developed technique for examining thermal sensitivity during sleep was used to assess whether skin and core temperature responses to thermal stimulation were altered by sleep state. The technique was designed to probe thermal responsivity without altering core body temperature or inducing awakening. Twenty-seven young men and women were studied during a sleep deprivation night and a sleep night three nights later. Cold water stimulation of the face alternated with an equal period of rewarming across a 40-min cycle throughout the night. Skin temperature from the finger and rectal temperature were continuously assessed. Sleep continuity and architecture were largely uninfluenced by the thermal stimulation. Finger skin temperature decreased during cold facial stimulation in both sleep and waking states. Skin temperature changes during sleep were approximately one-fifth the magnitude of those during waking. Core temperature was minimally influenced. REM sleep was associated with a greater amplitude decrease in finger temperature than was non-REM (NREM) sleep. The results support the utility of the technique as a probe of thermal responsivity during sleep and suggest a reduction of thermal responsivity during sleep and, more tentatively, an altered responsivity during REM versus NREM sleep.

Adult↗

PubMed1993

Reliable responses to a cardiovascular reactivity protocol: a replication study in a biracial female sample.

This replication study was designed to examine the reliability of individual differences in cardiovascular responsivity to a standardized PC-based cognitive task protocol (Kamarck et al., 1992) in a female community sample. Thirty women, both black and white (ages 25-44 years), were administered the protocol twice with a 1-month retest interval using a mobile laboratory at a community-based testing site. Measures of heart rate and blood pressure reactivity were obtained comparing assessments taken at rest and during three protocol tasks. Preejection period, stroke volume, and total peripheral resistance changes were estimated using impedance cardiography assessments. As in previous studies with males, individual differences in heart rate and systolic and diastolic blood pressure responses to the protocol were highly reliable (.80 or greater) when data were aggregated across three tasks and two testing sessions. Reliability of cardiac contractility (preejection period) and stroke volume changes to these tasks exceeded .70. This reactivity assessment procedure has now produced reliable results in three studies and appears to be exportable across diverse samples and settings.

Adult↗

PubMed1993

Are buckling force measurements reliable in nocturnal penile tumescence studies?

The study of nocturnal penile tumescence (NPT) is frequently used to evaluate male erectile dysfunction. Buckling force, a measure of rigidity, is an important part of this evaluation, but its reliability is unknown. Accordingly, we studied the reliability of buckling force measurement and the stability of "maximum buckling force" between consecutive NPT series repeated in the same subject. For individual subjects, we correlated buckling forces for separate episodes of sleep-related tumescence that were of comparable fullness (0-100%) as rated by a technician's visual estimates. For healthy control subjects, test-retest correlations were > 0.8 both within-night and across study series separated by an average of 70 weeks. In depressed men, correlations within nights were > 0.9, but fell to 0.64 across study series separated by an average of 21 weeks. Despite the high reliability of buckling force measurement, we found little stability of "maximum buckling force" between NPT series for individual subjects. Considerable variability in the maximum degree of penile rigidity was seen over time despite a constant level of reported daytime erectile function. We conclude that although penile rigidity is one of the more important variables in the assessment of male erectile dysfunction and can be measured reliably, the instability of maximum rigidity during sleep-related erections suggests that it is, at best, an imprecise correlate of daytime erectile function.

Humans↗

PubMed1992

Diminished nocturnal penile tumescence in depression: a replication study.

A descriptive study was conducted in a new sample of 51 men with DSM-III-R research diagnostic criteria (RDC) major depression in order to replicate earlier observations that measures of nocturnal penile tumescence (NPT) and penile rigidity are disturbed in depressive states. When compared to both the age-equated patient (n = 34) and normal control (n = 28) groups reported in our 1988 study, the new sample manifested significant abnormalities of NPT and diminished penile rigidity. Such disturbances were not, however, significantly correlated with psychobiological indicators of severe or endogenous depression.

Adult↗

PubMed1992

Early return to REM sleep after nocturnal awakening in depression.

Sixteen male outpatients with major depression and 20 age-equated healthy controls were awakened from rapid eye movement (REM) sleep between 1:30 and 3:30 AM, and the rapidity of return to REM sleep was determined. The time it took to return to REM sleep was reduced in depressives compared with controls: 61.6 (17.9 SD) min versus 80.6 (24.9 SD) min, respectively (p = 0.01). The time elapsed until the return to REM sleep was significantly correlated with baseline REM latency in controls (but not depressives). In contrast, return to REM time was significantly correlated with depression severity scores in depressives (but not controls). There was no evidence to support the hypothesis that the more rapid return to REM sleep in depression was caused by a slow wave sleep deficit. The mechanism underlying the rapid return of REM sleep in depression thus may be related to a severity-linked disturbance, such as a proposed increase in REM "pressure."

Adult↗

PubMed1992

On the synchrony of stopping motor responses and delaying heartbeats.

Recent evidence suggests that inhibition of a motor response may occur as late as the final stages of response execution. Response production involves central commands for autonomic support as well as motoric action. Autonomically controlled responses were used in conjunction with electromyographic and performance indices to examine the timing and flexibility of inhibition. Twenty young male Ss performed a choice reaction time task with stimuli timed according to when they occurred in relation to the R wave of the electrocardiogram. Stop signals, presented on 30% of the trials, induced inhibition. The performance and physiological results generally supported the horse-race model of inhibition. Inhibition was observed as late as during response execution. A short-latency, phasic lengthening of interbeat interval was suggested to reflect the midbrain coordination of the countermanding of response execution.

Adolescent↗

PubMed1992

Beat-by-beat cardiac responses in normals and schizophrenics to events varying in conditional probability.

Anticipatory cardiac deceleration and poststimulus acceleration were studied in schizophrenic inpatients and controls during performance of a counting task. Reduced cardiac responding has been reported for schizophrenic patients for paradigms using relatively long intertrial intervals. During a relatively fast rate of stimulus presentation (3-s interstimulus interval), changes in cardiac interbeat interval were measured in 20 inpatient male chronic schizophrenics and 18 control volunteers. Subjects counted an infrequent tone which was always followed by at least one frequent tone. Control subjects showed significant anticipatory cardiac deceleration preceding the unpredictable tones, whereas patients did not show a differential cardiac deceleration. Control subjects showed poststimulus acceleration that was inversely proportional to the conditional probability of events, whereas patients exhibited greatly reduced poststimulus acceleration; patterns for both groups resembled findings previously observed for event-related potential and pupillary dilation data. Analysis of cardiac cycle time indicated significant variation in primary bradycardia associated with the delay between stimuli and immediately preceding R-waves in controls (replicating Lacey & Lacey, 1980), with only an immediate bradycardia at stimulus reception for patients regardless of cardiac cycle time. The data reinforce the notion that the manner in which information is used by schizophrenics, as reflected by cardiac responsivity, differs both quantitatively and qualitatively from that of controls.

Acoustic Stimulation↗

PubMed1992

Is it important that the mind is in a body? Inhibition and the heart.

The hypothesis is advanced that certain inhibitory processes necessarily involve autonomic adjustments. Such adjustments would represent a constraint on information processing imposed by the location of the mind in a body. Evidence is reviewed showing that motoric inhibition is related to a transient delay in heartbeat generation. The delay is shown to further depend upon when inhibition occurs in the cardiac cycle. It is argued that this form of interaction between central and autonomic nervous system processing may be common. Central nervous system processes that may control inhibition and integrate information processing with motoric and autonomic processes are discussed.

Autonomic Nervous System↗

PubMed1992

Reliable measures of behaviorally-evoked cardiovascular reactivity from a PC-based test battery: results from student and community samples.

This paper describes efforts to reduce measurement error in the assessment of cardiovascular reactivity by standardizing task requirements and by aggregating data across tasks and testing sessions. Using these methods, reliable measures of reactivity (.80 or greater) were obtained on five different measures of cardiovascular function (heart rate, systolic blood pressure, diastolic blood pressure, stroke volume, pre-ejection period) in samples of college students and community volunteers. Methodological limitations may have hampered previous efforts in this area. Current findings are consistent with a dispositional model of cardiovascular reactivity, and they suggest productive future strategies for obtaining reliable assessments.

Adult↗

PubMed1992

Alternate cardiovascular baseline assessment techniques: vanilla or resting baseline.

The accurate evaluation of cardiovascular reactions to psychological challenge requires stable baselines against which change can be evaluated. When more than one challenge is employed, the recovery of this baseline becomes important in order to avoid carryover effects. Resting periods, even those of 20 min or more, do not guarantee baseline stability. We compared a 20-min resting condition and a new form of baseline condition in 48 college men using video tasks as the psychological challenges. The new form was a minimally demanding color detection task, termed the "vanilla" baseline condition. A 10-min version and a 20-min version of this condition were tested. Comparisons to 10-min resting baselines were made using our prior work and values from the literature. Vanilla baseline conditions were shown to be equal to or better than resting baseline conditions using criteria of between- and within-baseline stability, amplitude and significance of responsivity, and generalizability between sessions on separate days. Ten-minute resting baselines also showed acceptable stability, questioning the value of lengthy baselines. The good performance of the 10-min vanilla baseline in initial and replication samples supported its utility for estimating baselines for many purposes.

Adolescent↗

PubMed1992

Building a research program. Interview by Donald E.L. Johnson.

Faced with shrinking funds for medical research, hospitals have had to evaluate the role of research and reexamine how research programs are funded and structured. In the following interview with Health Care Strategic Management's Donald E.L. Johnson, Jan R. Jennings, president of Millard Fillmore Hospitals in Buffalo, N.Y., discusses how critical a research program is to a teaching hospital. The major benefits are improving the quality of care and creating a more dynamic and stimulating environment. But there are pitfalls, as well. Clinical research must be run with strict financial discipline and monitored from ethical and legal standpoints.

Chief Executive Officers, Hospital↗

PubMed1992

Results of nocturnal penile tumescence studies are abnormal in sexually functional diabetic men.

Nocturnal penile tumescence (NPT) studies are commonly used in the assessment of sexual dysfunction in diabetic men. While much of the evidence in favor of its use has come from the observation of markedly abnormal NPT in impotent diabetic men, little research has focused on the quality of nocturnal erections in sexually functional diabetics. Ten diabetic men who reported normal daytime sexual function were studied with 4 nights of polysomnography, including NPT assessment. They had significantly diminished NPT profiles when compared with that of an age-matched, nondiabetic, healthy control group. Without controlling for the effect of diabetes on NPT, between 70% and 90% of sexually functional diabetics had NPT profiles in a range that would be classified as indicative of organic sexual dysfunction for a man presenting for evaluation of sexual dysfunction. The finding of NPT abnormalities in a diabetic man should not be taken as evidence for irreversible sexual dysfunction. Rather, the condition of diabetes appears to result in NPT abnormalities, regardless of the adequacy of daytime sexual function.

Adult↗

PubMed1991

Forearm, chest, and skin vascular changes during simple performance tasks.

Momentary changes in vascular variables were examined in four experiments which all induced preparation for an expected stimulus. Response requirements were minimized to permit examination of changes during stimulus presentation unconfounded with overt movement. The hypothesis examined was that vascular changes serve to maximize tissue perfusion at the time of anticipated action. Impedance plethysmographic measures of the chest and forearm were scored both for transit times and amplitude/slope indices. Similar indices were derived from photo-plethysmographic signals from the nail-bed of the thumb. The results suggested that preparatory vascular changes could be divided into an initial expectancy phase started at least 2 or 3 seconds prior to the anticipated events and a specific preparatory phase occurring just prior to and during stimulus presentation. Transit time shortening and maintained vasoconstriction characterized the initial expectancy phase when a finger movement, but not an effortful grip, was the anticipated response. Transit time lengthening and vasodilation generally characterized the specific preparation phase, but are disrupted when a signal inhibiting the response is likely to occur. Decelerative heart rate changes were positively related to the slope of the systolic rise in the chest impedance measure, suggesting that both cardiac and vascular changes may act together. Overall, the results were moderately supportive of the view that the heart and vasculature act together to maximize tissue perfusion at the time of anticipated action.

Adolescent↗

PubMed1991

Acute tolerance to the cardiovascular effects of nicotine.

Acute tolerance to cardiovascular effects of nicotine was examined by presenting to male smokers a single administration of each of three different doses of nicotine (0.5, 1.0, 2.0 mg) or a placebo (0 mg) in a brief series of nasal spray boluses to mimic nicotine intake via smoking. Each dose was presented on a separate occasion. Changes in heart rate, systolic and diastolic blood pressure, finger pulse amplitude (peripheral vasoconstriction) and, in a subsample, plasma nicotine concentration were assessed during and after dose administration. Acute tolerance to nicotine was determined by comparing responses at ascending plasma nicotine concentrations during dose administration with the responses at comparable descending plasma concentrations following administration. For each nicotine dose, there was substantial acute tolerance to blood pressure, but less tolerance to heart rate (except for 0.5 mg), and little tolerance to pulse amplitude responses. These findings indicate that cardiovascular adaptation to nicotine during cigarette smoking may be rapid but variable in magnitude depending on the response being measured.

Administration, Intranasal↗

PubMed1991

Smoking as a cue for subjective and behavioral responses to a stressor.

Smoking in conjunction with a repeated stressor may come to serve as a cue, or discriminative stimulus, for responses to the stressor. This study examined the effects of omitting a previously predictable smoking cue on subjective and behavioral responses to a stressor. Male smokers were instructed to smoke briefly on command immediately prior to ("smoke-pre", n = 10) or several minutes after ("smoke-post", n = 10) each of four acquisition trials of a mental arithmetic task. During two subsequent trials, both groups first engaged in the task without the smoking cue (Test Trial 1), a novel experience for smoke-pre, and then engaged in the task preceded by the smoking cue (Test Trial 2), a novel experience for smoke-post. Omission of the smoking cue during Test Trial 1 produced significantly poorer task performance and greater subjective stress in smoke-pre. Although not significant, insertion of the smoking cue during Test Trial 2 tended to produce poorer performance in smoke-post. Thus, a consistent pattern of smoking in association with a repeated stressor may subsequently lead to impaired responding to the stressor if smoking is omitted.

Adaptation, Psychological↗

PubMed1991

Biobehavioral factors in sudden cardiac death.

The authors examine the recent literature on psychological factors and sudden cardiac death and explore the mediating psychophysiological processes by which these variables may be associated. Direct evidence that psychosocial stressors and their correlates may be causally linked with sudden cardiac death in humans is not conclusive, but there is abundant convergent evidence that several physiological precursors of sudden death may be promoted by psychological challenge, especially in persons with coronary heart disease. The authors call for increased attention to the acute effects of psychological events on cardiovascular health.

Arousal↗

PubMed1991

Electroencephalographic sleep in the healthy "old old": a comparison with the "young old" in visually scored and automated measures.

This report extends the normative study of sleep into healthy 80-year-olds and compares them with healthy 70- and 60-year-olds. We observed stability of sleep efficiency and rapid eye movement sleep across three decades of late life, but a slight decline of slow-wave sleep in the 80-year-olds (decreased total delta wave counts). Women showed better preservation of slow-wave sleep than men. Automated EEG period analysis of this phenomenon demonstrated higher rates of delta wave production in the first NREM sleep period of women compared to that of men, a finding associated with longer REM sleep latencies in women. Unexpectedly, 80-year-old women showed decay in sleep maintenance, while 80-year-old men demonstrated stability of sleep maintenance, relative to their respective 60- and 70-year-old counterparts. Implications for the understanding of sleep and its regulation in health and aging are discussed.

Aged↗

PubMed1991

Circadian characteristics of healthy 80-year-olds and their relationship to objectively recorded sleep.

Thirty-four healthy older adults (self-described "good sleepers") in their ninth decade of life (16m/18f, mean age 83.1) were compared to 30 young controls in their third decade (21m/9f, mean age 25.5) with regard to: (a) circadian and personality characteristics as measured by the Horne-Ostberg Morningness Questionnaire (HOM), Circadian Type Questionnaire (CTQ) and Eysenck Personality Inventory (EPI); (b) measures of habitual bedtime, waketime, and time in bed from a 2-week sleep diary; and (c) polysomnographic measures from a (post-adaptation) night of sleep recording in the laboratory. In almost all laboratory measures the older group slept poorly compared with the young, acquiring about one hour less total recorded sleep. The older group showed earlier habitual time of waking than the young, and showed higher (more "morning-type") scores on test instruments (HOM, CTQ-M) designed to assess morning-evening orientation. They also showed a lack of flexibility in sleep patterns (higher CTQ-Rs score) and less intersubject and intrasubject variability in habitual sleep timing compared to the young. Older subjects' morningness test scores were significantly associated with objectively measured sleep durations, with a tendency toward "morning-type" circadian orientation being associated with longer sleep.

Adult↗